How to build a Pergola
Softwoods are committed to providing our customers with all of the care and advice that we can, and we are happy to present here our comprehensive instructions for building a pre cut Softwoods Pergola. This is an extremely long and comprehensive document that will help you through each and every aspect of the building of your structure. For ease of navigation and reading it has been broken into several posts that cover all of the elements required in your build.
This particular set of instructions is for a parallel attached gable roof pre cut pergola kit. Our pre cut pergola kits make the construction of a pergola considerably easier than previously because all of the angles and notches are cut to create a kit that will fit together simply, without the requirement of endless measuring and cutting.
Our assembly method also benefits from pre cutting, allowing a lot of the work to be done on the ground which makes for a safer build. In addition to these instructions there will be further posts on how to install Hip ends, freestanding pergolas and decks in future.
As a guide for you, most of our carpenters can finish a 6×4m parallel attached structure in approximately two days. We would advise that you should take your time and make sure that you are doing everything methodically and properly as it will save you time and money if you get everything right the first time. Following our instructions should mean that you are able to build your pergola as easily and quickly as possible.
Please click through to each article in the series for each step in the process.
Step One – What you need to consider before you build
Step Two – Identifying the elements of your Pergola
Step Four – Assemble Gable Frames
Step Five – Installing Fascia Brackets
Step Six – Installing Beams and Bottom Chords
Step Eight – Installing the Rafters and Ridge
How to Build a Pergola – Step One
What You Need To Consider Before You Build
In building a Pergola, you can save yourself a lot of time and hassles down the line if you give some consideration to a few things before you start.
It is very important to check with your local council or shire before building any structure. It is your responsibility to ensure that all relevant approvals have been obtained and that the structure that you are attaching to (likely your home) is suitable to support the additional load imposed by your new pergola. In the absence of approval, a council or shire can reasonably demand that any structure you have built be pulled down. Obviously this is not a desirable outcome so we strongly recommend that you get your approval first!
Most local councils or shires require an application to be lodged detailing the proposed works and whether they meet engineering standards and local guidelines. Generally speaking a fee is required to lodge an application, and an approvals process is undertaken which usually takes a number of weeks (the timing can vary wildly from council to council) Plans and elevations are needed with the application, and if there are any issues your council or shire will usually contact you for clarification or further engineering.
If you are using Softwoods for your materials we will provide your plans and elevations free of charge for your application, and all of our pre cut structures are certified by our engineers. We also have a plan service, which charges a nominal fee for the preparation of plans for you should you require them.
Once you have approval, you will need to ensure that you have all of the necessary materials to make building your Pergola as safe and simple as possible.. Below is a list of these tools.
Easily the most important thing that you need to do in preparing to build your pergola is to create a safe work site. As you will no doubt understand, your well being is essential and it’s worth making sure that you feel safe at every stage of the building process.
Various stages of construction will require at least two people to complete so make sure that you have some helpers on hand for these. Also ensure that appropriately tall ladders are used when required and that your work site is clean and clearly flagged during construction to avoid children or other unauthorised people entering the potentially dangerous area. You will find handy safe work methods and tips on our website which we advise you to read carefully
It is also worth your time to make sure that if your timber is delivered in advance of your intended build date, that you ensure it is stored correctly. Timber will be subject to some movement if not stored correctly, so please ensure that it is tightly packed, off the ground and in a dry area (avoiding placing it on lawn is a good idea)
The last thing that you need to consider before you start to build is the painting of your timber. Not many people enjoy this part, but unfortunately it needs to be done, as a painted structure will withstand the weather infinitely better than one that’s unpainted. Again if you are buying your materials from Softwoods we can offer a painting service and deliver you your materials fully painted and only in need of a minor touch up upon completion of your build.
Use two painting trestles, and a roller or spraygun to paint all of the timber, and ensure that you use the paint to the manufacturers specifications. It’s important to get the painting right while the timber is on the ground as it is very difficult to repaint once your structure is built. Once you have painted your timber, store it with spacers so that the timber wont stick together as it dries. Once you are done with painting, it’s time to commence the build!
How to build a Gable Roof Pergola – Step Two – Identifying the elements of your Pergola
How to build a Pergola – Step Two
Step Two- Identifying the elements of your Pergola
In order to successfully put together your pre cut pergola kit, you will need to be able to identify all of the elements of the structure. Furthermore we will be referring to all of the pieces by their names from here on in, so it makes sense to establish what is what at this point.
Your kit will be delivered with a bill of materials and a cutting list. The names of each timber on the list correspond to their names in the diagram below (click on the diagram to enlarge it) Before building anything, conduct a thorough check to ensure you have every piece of timber.
To help you identify and assemble the timber members they have been marked. The markings are on the cut ends so that they will be visible when the timber is painted and not visible once the structure is complete. There are some members that you will need to mark, however we recommend that you should paint all members before marking anything.
Corner Posts are marked with a PC# on the notched out sections
Intermediate Posts are marked with a PM# on the notched out sections
Beams are marked with a BM# on the topside at one end
Bottom Chords are marked with a BM# on the topside at one end, the bottom chords have a notch in each end.
Standard Rafters are marked with a RS# on the topside at one end
Gable End Rafters are marked with a RG# on the topside at one end
Collar Ties are marked with a CT# on the topside at one end
The Ridge is marked with a RDG# on the topside at one end
Purlins are marked with a PR# on the topside at one end
Vertical Struts are marked with an ST# on the end cut
Starburst Struts are marked with a SB# on the end cut
Barge Boards are marked with a TB# on the internal face at one end
Once you have identified all of the timbers and painted them it’s time to start marking out
How to build a Gable Roof Pergola – Step Three – Marking Out
How to build a Pergola – Step Three
Step Three – Marking out
Once steps one and two are completed it’s time to begin marking out your pergola. Marking out your pergola is not unlike a preparing food before you cook. Being well prepared allows you to put your pergola together quickly and easily, and means that you won’t have to stop or go back in the middle of building.
A major benefit of a Softwoods pre cut gable pergola is that a lot of the measuring and marking has been done for you. Other tasks that would have previously been done ‘in the air’ when the structure is partly constructed can now be done safely and accurately on the ground.
This makes the building process safer, quicker and easier for you. The key benefits of accurately marking at this point are that it will ensure that everything goes together accurately and quickly once you assemble the structure.
If you are marking and cutting your own pergola, this part of the process is EXTREMELY important, as it’s integral to your structure going together in an orderly manner. You will need to calculate all of the angles required to get the correct pitch for your structure, cut them accurately (as well as your posts and bottom chords) And you will need to measure the spacings for your rafters and purlins.
Fitting Joist Hangers to Beams
The beams (members marked with a BM#) have the positions of the rafters already located on them. About every 1200mm (exact measurement depends on your structure) there will be three holes punched into the face of the timber. Holes 1 and 2 line up with corresponding holes in the joist hanger. Hole 3 forms a triangle with holes 1 and 2 to indicate the top side of the beam.
To fit, line up the joist hanger holes just above the single gang nail on flange with holes 1 and 2 on the beam. Drive a connector nail through the joist hanger into hole 1 leaving the head of nail just proud so that it can be pulled out if it clashes with the bolts of the fascia bracket fitted at a later stage.
Squeeze the joist hanger so the central hole on the opposite flange is aligned with hole 2 on the face of the beam. Drive another connector nail through to complete the temporary attachment of the joist hanger to the beam again leaving the nail just proud. The remaining connector nails will be fitted after the rafter has been located in the joist hanger.
Repeat this process for all the joist hangers required in the structure. The result will be two beams with joist hangers positioned exactly to receive the gable frames.
Marking Rafter Positions on Purlins
The purlins (members marked with a PR#) are fitted to the top of the rafters after all gable frames have been installed. Pre marking on the purlins exactly where they should intersect with the rafters will allow the rafters to be easily pulled into square when the purlins are installed.
Arrange the purlins side by side on a level surface or on saw horses. All of these members will be the same length. Position the beams with joist hangers attached so that they are on either side of the group of purlins and so that the ends of all members line up. The arrangement should look like the image below
Use an off cut or straight edge to mark a line across all of the purlins to correspond with the edge of the joist hangers. The result of the marking out is illustrated below
Repeat this process for the other joist hangers. The result will be two lines marked on each purlin that represent the position of each rafter.
Marking purlin locations on rafters
The last members you have to mark are the rafters.
Have a look at your plan you will be able to see how many spaces between the purlins there are on your structure. Measure the top edge (or run) of one of your internal rafters and subtract 70mm from this length. Once you have that number, you will then need to divide it by the number of spaces. This is the distance from the top (closest edge to the ridge) of one purlin to the top of the next purlin. Mark this out on your rafters leaving out the bottom mark as that will be determined by the edge beam and the internal gutter.
For Example:
If x = 2400
Then 2400 – 70 = 2330
2330 divided by 3 spaces
2330/3 = 777 (round up)
Based on this calculation, you would place a mark 777mm from the top of the rafter then another mark 777mm down from that. Please remember that you don’t need to mark the top or bottom purlin position.
Marking rafter locations on ridge
The top side of the ridge will have small scores along it to indicate where the centre of each rafter will go. Similar to the number 3 holes marked on the beam.
Once this has been completed, it’s time to begin to assemble your gable frames in the next step.
How to build a Gable Roof Pergola – Step Four – Assemble Gable Frames
How to build a Pergola – Step Four
Step Four-Assemble Gable Frames
The next step in building your Softwoods pre cut gable pergola is to assemble your gable frames. It’s at this point that you might finally start to get the feeling that you are actually building something! However as with the previous steps, this step is also preparation for the building to come.
Gable frames consist of the internal rafters and collar ties, which are made into an A shaped frame to be lifted into the structure once the beams have been installed. Your gable frames will provide the internal shape to your structure, so it’s important to make sure that they are all of a uniform shape and size. Your frames will be made on the ground then lifted into place later. You will need to do this on a flat surface for the most accuracy.
Layout rafters with bottom chord and ridge block
Lay the bottom chord on timber blocks (rafter stiffeners) on a flat surface and then place 2 rafters with their ends on the inside of the mitre (see the diagram below for a clear picture). The rafter edge will line up with the vertical face of the notch as well as the angle of the rafter.
Using a ridge spacer (supplied in the hardware box) as a makeshift ridge, move the rafters so they meet the ridge spacer at the top. Make sure the rafters are still in the correct position against the bottom chord. The rafters and ridge should look like the diagram above, and need to be elevated on rafter stiffeners as described previously so that it is easy to drill through the rafters in the coming steps.
Place collar tie
Once rafters are in position, place the collar tie on top of the pair of rafters with the cut edge following the angle of the rafters. The rafters and collar tie should form an A shape.
To establish the exact position on the rafters that the collar tie should sit, measure from the edge of the rafter to the edge point of the collar tie on both sides and check if they are about the same. If you are unsure, have a look at the diagram below for the point that you should be measuring.
You may need to move the collar tie a few times until your measurements are the same or similar.
Drill and bolt collar ties
Drill 10mm holes for your bolts through the collar tie and rafter using the table and diagram below to determine their quantity and placement. You can clamp the collar tie to the rafters as you drill to make sure that there’s no movement of the frame as you drill.
Once the holes are drilled insert the bolts through the rafter and collar tie. You will need to knock the bolts in with a hammer. Because of the tight holes, the frame will be held firmly in place. There is no need to fix with washers and nuts at this stage.
Now your first gable frame is almost done. To continue with the next frame, place another set of rafters and a collar tie above the frame you’ve just made (see example below)
Line up the rafters and the collar ties so they are parallel with the first frames components. This should allow you to easily and accurately recreate the first frame, using the ridge block and the angle of the previous gable frame as a guide.
To make sure your collar ties all line up when the frames are installed, measure the distance between the two at both ends. If it is the same, the collar ties should all be straight.
Once you are confident that your new frame is in the correct shape, mark and drill the holes for your bolts through the collar tie and rafters as before, inserting the bolts once you are done. Repeat this process until all of your gable frames are assembled with bolts inserted on the ground, and then stand the frames up one by one and fit them with washers and nuts and tighten.
All of your gable frames should now be finished. Store them in a dry safe place until they are needed.
You can now move onto the next step, Installing Fascia Brackets.
How to build a Gable Roof Pergola – Step Five – Installing Fascia Brackets
How to build a Pergola – Step Five
Step Five-Installing Fascia Brackets
The next step in installing your pergola is one of the most important. Fascia brackets are the method by which your pergola will be attached to your home. They form a strong bond between your house roof and your pergola, making sure that both your home and your pergola will not be affected by any weather or the weight of your structure.
Fascia brackets are designed to take the load of your pergola back into your home’s roof and make sure that this load is not borne by the house fascia.
It is very important to install your fascia brackets correctly to ensure sufficient structural support for both your pergola and your home. Fascia brackets and stiffeners are installed at 1200mm centres.
Install rafter stiffener
To install rafter stiffeners to your house rafters you will need to temporarily move your existing roofing so that you can have access to the rafters. Rafter stiffeners are lengths of timber that are used to provide additional support to the house rafters. Fascia brackets attach directly onto them.
Getting access to the house rafters can be achieved by unscrewing the metal sheeting or lifting up tiles. If you have a sheet roof, use an off cut or a couple of short props to make a cave like area to work in. However, be very careful not to crease your sheets in doing so.
Once you have access to the house rafters, use 75mm bullet head nails to fix the 70 x 35 rafter stiffener to the house rafter in a zig zag fashion with a maximum spacing of 100mm
Cut slot in fascia
Using a pencil, draw a line on the inside of house fascia lining up with the outside face of the 70 x 35 stiffener you have just installed. Use a straight edge to follow the outside edge of the stiffener around the house gutter and onto the outside of the fascia and mark this point. Cut a 60 x 7mm vertical hole through the house fascia starting just underneath the gutter. Before you cut anything double check that your first hole is located beneath the gutter’s lowest point.
Install end fascia brackets
Slide the bracket up through the slot you have just cut so that the outside face of the “T” section is flush with the outside of the gutter. Once the bracket is in position, drill holes and insert bolts through the rafter stiffener and rafter using 4 x M10 bolts.
Install the two end brackets first and use a string line to make sure the remaining intermediate brackets are all level. Once you have installed intermediate brackets, you can refix the house roof and proceed to the next step, installing the beams and bottom chords.
How to build a Gable Roof Pergola – Step Six – Installing Beams & Bottom Chords
How to build a Pergola – Step Six
Step Six – Installing Beams & Bottom Chords
At this stage of your pergola’s construction, you are probably wondering when you will actually get to do some building. The answer is right now. By this point, you have successfully prepared yourself to build your own pergola in the simplest safest and quickest way possible. It’s time to start building the frame of your structure.
Install fascia beam
Now that you have your fascia brackets in position it is time to put up the fascia beam. The beam is to be bolted onto the brackets with 10mm diameter cup head bolts. Obviously it’s a much better idea to drill your bolt holes on the ground than in the air, but in order to do so we must first determine the required position of the holes so that they fit the brackets.
Lift up the beam (with someone else’s help) and hold it against the brackets ensuring the top of the beam is in line with the top of the gutter. Your gutter probably falls to one side so it’s best to line it up with the gutters highest point. Once you are happy with the position of the fascia beam clamp it to at least two of the fascia brackets so that it is held securely in place. Use a spirit level to ensure the fascia is sitting level. Then, using a pencil, reach around the back of the beam and trace around the inside of two of the bracket holes for every bracket.
Once you have completed this for every bracket you can un clamp and take the beam down and drill through all of the holes you have marked.
After all of the holes have been drilled, pick the beam back up and place it against the matching fascia brackets, making sure that the beam is the right way around. Fix the beam in place with 2 x M10 cup head bolts for every bracket.
Install bottom chords
Once the fascia beam is in place and level you can commence the installation of the bottom chords. The first thing that you must do is half nail 2 x 75mm bullet head nails to each end of the bottom chords. This will make it easier to nail into the fascia beam once the bottom chord is in place. Use the picture below as a guide.
Using a prop for support, position the bottom chord at the end of the fascia beam (Many types of props are available for hire. You can also clamp or nail a purlin to the beam as a makeshift prop) temporarily fix the bottom chord to the fascia beam with the nails you have half nailed into the mitred ends.
Repeat this process and install the other bottom chord to the other end of the fascia beam. Once you have both bottom chords attached check that they are both level. Also make sure that the notched sections on both bottom chords are positioned on the top of the chord.
To complete the connection between the bottom chord and the fascia beam a heavy duty L bracket is used.
Position the L bracket in place then select two holes on each face of the bracket and drill through. Fit 2 x M10 bolts on each face of the bracket, fit the nuts and tighten to secure the bottom chord in place. The prop will be required to hold the chord up until posts have been installed and fastened.
Install perimeter beam
The perimeter beams are completed with the installation of the main beam which connects the two bottom chords.
Partially nail 2 x 75 bullet head nails in both ends of the beam as you did with the bottom chords to make it easier to attach to the chords when the beam is lifted into position.
Lift the beam into position (with somebody’s help and using props about a metre from each end of the beam) so that the mitres at either end of the beam marry in with the mitres of the bottom chords. Your beam should fit perfectly.
Fix the beam to the ends of the bottom chords with the temporary nails that you have in position. These two corners will be secured with the installation of the corner posts, so there is no need for an L bracket at this point. However the chords and beams must be well supported by props so that no movement occurs.
Before proceeding with the installation of posts it is important to check that the frame is square. This can be done by measuring the width and length in two or three places along the structure. Or for a more accurate method, use the diagram below. Lines 1 and 2 should be of equal length, 3 and 4 equal length. Join the diagonally opposite corners with a string line making lines 5 and 6, checking that the string is the same length. This method ensures that all sides are parallel and square.
Once you are sure that your frame is square and level you can move on to the next step, Installing your Posts
How to build a Gable Roof Pergola – Step Seven – Installing Posts
How to build a Pergola – Step Seven
Step Seven-Installing Posts
The frame of your Softwoods pergola is almost complete and now it’s time to install posts to make the structure stand up. This step is once again very important to get right as once the posts are set it’s extremely difficult to fix any mistakes you have made to this point. Once you have the posts installed you will really be able to see some progress in your pergola and all of the preparing and marking out that you did earlier will start to pay off for you.
Marking the beam
From your plans you can work out where the posts are to be located. Measure and mark the centres of the post locations on the beam with a pencil line indicating where the centre of the post will be.
Measure and cut post to length
To determine the exact length the post needs to be, a few measurements are required. Firstly measure from the top of the beam at the position of each post, to the point on the ground where the posts will be fastened.
As the posts do not go to the very top of the beam, you will need to subtract from the measurement that you have a Post Set Down (PSD) amount, which is the depth of your beam minus the depth of the notch out on the post.
Finally, the amount the post will be above the ground is also required to be subtracted. This may vary depending on the style of post shoe you have or whether you plan to pave in the future. Use the diagram below to help you.
Just to be clear, the exact length of the post is the total height (from the top of the beam to the floor) minus the Post Set Down minus the ground clearance.
Once you are certain that you have this measurement correct carefully cut the post to this length with your power tools. After you have cut the post be sure to spray the cut ends with a timber preservative.
Fit the post shoe
Now that the posts have been cut to the correct length the post shoes need to be fitted for each post. Follow the appropriate instructions from the previous diagram to suit the post shoe type you have. Please pay particular attention to ensure that the base of the post is the distance you require above the seat of the post shoe.
Determine location of post hole and dig hole
Once you have all of your posts fitted with shoes you can move on to digging the holes to fit your posts and then concreting in the post shoes. Holes are located directly under the posts so that the posts can be easily plumbed.
A simple ‘plumb bob’ can be made by attaching a weight to the end of a piece of string. Attach the other end of the string to the beam at the position you have marked for the centre of each post. Let the weight hang just above ground level (you may need to adjust the length of string to achieve this) and (barring any howling winds!) it will be located directly above the centre of where you will need to dig the footing hole.
You will find the required footing size for your posts on your plans. Dig a hole to these dimensions at every point that a post is required. It is important that you make sure that your footings are the correct size as they are essential in anchoring your pergola in extreme weather conditions.
Fit the post and pour concrete
Now that you have your holes in place, you can fit the posts to the beam. The posts are to be fitted to the beam while the structure is still on props so that the beams don’t fall with the posts into the holes. Once the posts are fitted, the shoes should sit above the bottom of the holes that you have dug for them. This way you can fill the holes around the shoes and they can set in exactly the right place.
You should have already worked out where the centre of the posts are supposed to be on your beams, and marked this point. From this point, measure outward half of the width of the post in both directions from this mark. Eg an 88mm wide post measure and mark 44mm each side of the centre. This will locate where the edges of each post will be fixed.
Lightly project these marks down the face of the beam to provide a guide for lining the post up. To position the post place the post shoe in the hole first and lift the post up so that the beam rests nicely in the pre cut notch.
When the post aligns with the markings each side, clamp post and beam together. Final, small adjustments can be made by loosening and tightening your clamps.
Make sure that the post is level and when you’re satisfied that it is, drill through the post and the beam, using you spirit level to make sure that the post alignment is correct. Bolt the post to the beam using 2 or 3 M10 bolts. Make sure that you have the bolt heads on the outside of the beam.
Once you have fastened each post, mix your concrete according to the manufacturers instructions and pour it into the footing holes. Before you pour any concrete, do a last check to see that your beams and bottom chords are level as well as your posts.
Pouring the concrete, unless done very carefully may cause the post to be moved out of level – quickly check each post after pouring and return it to level if this occurs. Repeat this for all of the posts and also check the levels of previous posts as you go.
Once all of the concrete is poured, and all holes are filled, you should leave the structure propped until the concrete has set. It is best to leave it over night as working on the structure may result in your pergola being moved out of square as the concrete cures. Once the concrete has completely set, you can remove the props as it will now stand alone.
Now that you have completed this step, you can move onto the next phase, Installing the Rafters and Ridge.
How to build a Gable Roof Pergola – Step Eight – Installing the Rafters and Ridge
How to build a Pergola – Step Eight
Step Eight- Installing the Rafters and Ridge
Once the frame and the posts are installed, your pergola will look like it is beginning to come together. It’s now time to receive the payoff from your earlier work assembling gable frames. Erecting the gable frames is a quick and simple step and will leave you with what looks like an almost finished gable pergola. Putting the frames up is probably the easiest and the most fun part of your project.
The frames are installed with a minimum of two people per frame(Illustrations here only have one person, but we recommend two) To put them in place, stand a ladder at each beam below the corresponding joist hangers which you have already installed. Lift one end of the gable frame into one of the joist hangers so it is pushed in as far as possible.
With one person holding the end that’s in the joist hanger in place, lift the other end up to the opposite joist hanger and slip it into place also. Ensure you keep the first end of the gable frame securely positioned in the joist hanger while you do this as you could either break your gable frame or injure yourself if the frame falls. Once both rafters are in place push both down firmly to ensure they are positioned completely in the joist hangers and against the beams.
Once the gable frame is up and firmly in place, secure each side by driving a flat connector head nail into each hole of the joist hanger.
Repeat this process for all of the gable frames in your structure. Be careful to make sure that you position all of your frames with the collar ties on the same side.
Installing the ridge
Now that all of the gable frames are up and securely fastened you can move on to installing the ridge. The first step in installing your ridge is to gently slide it into the gap above your collar ties and below your rafters. The ridge should sit on top of the collar ties and run the length of your pergola.
With a ladder at each end alongside the bottom chords, 2 people should be able to lift and push the ridge beam into position in the gap at the top of both sets of rafters. Make sure that when you do this the notch in the ridge is on the under side.
Once in position, the top of the ridge beam should line up with the top of both sets of rafters. The rafters will support the ridge but you should be careful not to push it too far up as it can be quite difficult to pull down. Once the ridge is in place you can use your spirit level to make sure the end of the ridge is lined up with the outside face of the bottom chord.
If the centre of the rafters do not line up with the marks on top of the ridge you will need to tap them into place. Do this using a block to protect the timber of the rafters from damage by the hammer.
Once the rafters are in place fix them to the ridge with 3×75mm nails, 1 in from the top of the rafter and 1 skew nailed in either side. As you fix each gable frame to the ridge you can also fix the 600mm rafter strap over the top of the rafters and ridge. To do this, use 5 connector nails in the holes on the strap on each side of the ridge.
Now that you have completed and fastened your gable frames and your ridge, you can move onto the next step, which is the installing gable ends and purlins
How to build a Gable Roof Pergola – Step Nine – Installing Gable Ends and Purlins