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Build Your Own Summerhouse – Part 3, Wall Frames & Deck

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Build Your Own Summerhouse – Part 3, Wall Frames & Deck

Reading Time: ~ 6 minutes

Writing about how to build a summerhouse is taking me considerably longer than it did to actually build one. If you didn’t already see the posts on how to do the groundwork and the floor frame then you might want to check those out first. This time we’re creating the wall frames and front deck.

Previous Stages…

Materials

The wall frames are built from scant with 100mm x 6mm woodscrews. I skinned them in OSB/2 and covered them in the same insulating aluminium vapour barrier as the floor frame. It is possibly a little over-engineered (as is often my way). However, it’s stood for over two years at the time of writing without even a hint of movement, so…

Planning

You should already have a good idea of how you want your summerhouse to look now. You’ll know the overall sizes from the groundwork stage. I planed the size of my summerhouse wall frames to consider a few things

  1. Space available – make the best use of the space you have by considering the angle and position as well as the size of your structure.
  2. Permitted development (Planning & Building laws) – look into the local laws on planning. Mine restricted, amongst many other things, the overall footprint and height of what I could build.
  3. Standard sizes of timber – it’s important to think about the lengths of timber you can get and plan around these. This will save both time and money.
  4. Visual proportions – perhaps most obviously you’re going to want this to look nice. The front is the most important elevation but don’t forget about how it will look from other angles too.
  5. Internal ceiling height – This was a bit of a challenge while staying inside permitted development. It drove the angle and style of roof. I basically worked backwards from the front edge of the roof; I set the height at what was legally allowed. The I made the roof angle so the back inside edge was high enough for tall people to stand up properly!
  6. Roof angle – linked to point 5, you need to make sure that you end up with at least 5° pitch on your roof. As I planned to have a live roof I did some research and found that 5°- 15° was ideal. If you’re not doing a live roof (boring) then you can set it at any angle you like as long as it drains.
  7. Structural integrity – critically, you need the thing to still be standing in years to come. I built all the walls using standard stud wall conventions. Technically, stud walls are non-loadbearing but by skinning with OSB and doubling up on the top plate and window headers I got a pretty strong structure.

Front wall

Use the width of your floor to mark out and cut your top and sole plates (the top and bottom pieces), double up the top plate. Then lay the pieces on the floor and mark and cut all of the studs. Remember to take into account the thickness of the top and sole plates by subtracting it from your studs. Screw the studs to your sole plate and one of your top plates and then screw your final top plate on. Be careful not to run your screws into each other. Then make up the rest of the frame by using the spaces between studs to mark the timber for cutting – it saves on measuring.

Top tip: Use an impact driver to put in your screws, it’ll save you so much time it’s even worth buying one if you don’t already have one.

The easiest way to get a nice edge around the windows was to fix full sheets of 12mm OSB. I then drilled a hole in one corner and used a flush-cut router bit to cut out the window. It saves a lot of time and doesn’t use any extra timber as far as I can see. If you’re careful, the pieces you get left over are still pretty useable.

Vapour barrier

There’s a variety of materials you could use here. Most people would probably opt for some sort of house wrap (like Tyvek, other brands are available). I used the same aluminium foil vapour barrier that I used on the floors. I planned to add ventilation so the “breathability” of the walls wasn’t a big concern. The foil also works as insulation, reflecting heat on a hot summers day and keeping the inside cool. It’s so effective that it can sometimes even be a little too cool in there when you first go in.

Cut the pieces long enough that they wrap right around the edges and staple them on the inside of the wall frames. Use aluminium tape to seal the joins. At this stage it’s better to go straight over the windows, it’ll keep everything weather tight until you add the roof and cladding.

“Your front wall crushing you while you build the others shouldn’t be part of your plan”

Attach a couple of temporary extra pieces of wood to the sides. When you stand it up you can screw them to the edge of the floor frame for support. Your front wall crushing you while you build the others shouldn’t be part of your plan. Screw the wall to the floor.

Front deck

My decision to use scaffolding boards as cladding was simultaneously one of my greatest and worst. The final product looks amazing but the amount of extra work, both physically (they’re heavy!) and time wise was considerable. I decided to put the deck down at this point as it was getting difficult and dangerous walking over the open floor frame.

Look around online for scaffolding boards, you can get some good deals. The ones I used were new but you could also use second hand ones and remove the strapping. I had originally intended to do this but, because they’re trendy at the moment, they actually cost more than new ones. Go figure.

Laying them out and cutting them to length was easy enough. The tricky part is the weight of the things; make sure they’re well supported before cutting. If you’re using a circular saw or a mitre saw this is very important. Letting the board sag as you cut can pinch the blade and cause some pretty serious kickback. Scary and super dangerous.

“because used scaffold boards are trendy at the moment, they actually cost more than new ones”

I used a 45-degree chamfer bit in my trimmer router to shape the edges of the boards. This shows how chunky the boards are and adds to the overall style of the build. There was a moment where I realised not only how long this would take, but also that I’d be doing it for all the cladding and other pieces too! It was a long job!

Create a small spacer and mark some depths on it to help with screwing everything down. I cut a small piece of scrap wood to the thickness I wanted to space the boards. Put in a screw and then mark how far from the edge of the board it is on your spacer. You can then use this as a depth gauge when putting in the rest of your screws. Don’t forget to tap pilots holes and countersink for all your screws.

Side and back wall frames

The side walls are fairly quick to build. Start by marking and cutting the sole plate by butting it up against the front wall and marking it at the back edge of the floor. Lay out the studs on the floor at the correct spacings with the floor plate at one end. Mark the front stud at the same height as the total height of the front wall minus the thickness of one piece of scant. Lay a complete length of timber on top of them and adjust its angle to give you the height you want at your rear stud. Use the top timber to mark the cut lines on each stud then mark that piece at the back of the wall using the rear stud. Adjust your mitre saw (if you’re using one) to the correct angle and cut all the pieces to length.

Screw the frame together, then add noggings about half way up. Make the opposite frame by laying pieces on top of the one you just built.

Fun Fact: OSB/2 is graded for structural walls in dry conditions. As opposed to OSB/1 which is not intended for load bearing and OSB/3 which can withstand humidity.

Next, add sheathing to both frames. Do this by laying the OSB on top of the frame and squaring it up to one of the factory edges. Mark your cut lines with a straight edge, slide the board over a bit and use a circular saw to trim the excess. Slide the boards back into place and screw them down. Add more insulating foil wrap, taking care to tape the joins and staple on the inside of the frame. Finally, stand the walls up and screw them to the base and to the front wall.

Back wall

Build the back wall in the same way you did the sides, except without the angle. I decided to put some notches in the top plate to seat the ceiling joists. This might not have been necessary, to be honest, however, it did make it easier getting them evenly spaced. It also meant there was no chance of them sliding over when I put sheathing on the roof. I got all this done, on my own, in one looooong day. Though I was so tired by the end of it I stapled my finger to one of the walls; don’t do that. The last step is to throw a tarpaulin over the top and staple it down.

These four walls

Wide Angle Inside

It’s amazing how satisfying standing inside a structure you just built feels. I think it triggers something deep down, like a triumphant caveman feeling. Or something. Maybe not.

Crin

Crin

A lifelong fan of making and breaking things. If you can do it yourself, why wouldn't you?

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