Jun 2021 - Walls
Quite early on in my planning I came to the conclusion that walls were an essential feature, I've not seen any garden rooms without them so who am I to buck the trend
Success factors for the walls as follows:
- studs spaced to accommodate sheet goods without unnecessary cutting / waste (400 centres for me)
- plumb, flat, level
Centres
400, 450 or 600 - those are the main options. I chose 400mm because its the strongest, and because it is compatible with metric boards either 1200 or 2400. You could use an imperial spacing also if you were using imperial boards, this would be expressed in inches for example 16 inch or 24 inch. I have already talked about metric versus imperial so I won't open the box again. OK, just a little bit... Just to make life fun for us all, plasterboard typically comes in metric sizes and OSB typically comes in imperial sizes. Those constraints represent a perfect combination for screwing up all our careful planning. I've already mentioned my plan in this regard earlier, but I will recap it briefly below:
- metric sized sheet goods
- 400mm centres spacing for studs and roof joists
- metric plasterboard on inside
- metric OSB on outside
if you are happy with 11mm OSB then you can get it in metric, yay. In the end I bought cement boards for the back wall and two side walls (in metric, 2400 x 1200), and I used the 11mm OSB boards for the front wall.
Plumb
Regarding the 'plumb' success factor this is super critical, particularly for studs that accommodate the sheet 'joins'. The reason being that each sheet you fasten to the studs (ply, plasterboard, cement board) will share a stud which is probably about 47mm thick. This gives you about 23mm for each sheet to fix to. If your stud is not plumb then you are going to create huge issues for yourself because sheet goods are famously 90 degrees square, and if your studs are not plumb then they are not square to the floor and hence won't be compatible with the sheet edges (which are very square). You end up with a taper instead of an even strip:
10mm spacing error results in a tapered target to fix to
I didn't fully appreciate sensitivity of this factor when I was building the walls, but realised it later once I was attaching sheet goods to them. Fortunately I am quite obsessive about details, often unnecessarily so, and hence spent some time getting the walls perfect, so I ended up doing a pretty good job of it as luck would have it.
Note: in reality you are not building the studs 'plumb', because you will most likely build the walls flat on the floor and then lift the wall up into position. You are in fact building the studs accurately and equally spaced top and bottom (where they attach at top plate and bottom plate), and then you can make the entire wall plumb once its upright. If your spacing of the studs is accurate top and bottom this will make each individual stud plumb and square once the whole wall is square.
Note: if you are just 10mm out on the stud spacing then you end up with only 13mm to fix to and that would also force you to screw into the sheet edge which is a weak point, particularly for plasterboard. Disengage lecture mode.
Marking
You can either mark the centres or the edges of the studs. You would also probably want to mark multiple studs at the same time to speed things up (might also help with accuracy)
Centres
It is easier to mark the centres, because you can simply hook the tape on the end of the bottom plate, and then mark every 400mm using a tape measure. The only issue with this is you have to then judge where the centre of the stud is when lining it up with your mark. It's not exactly difficult but it can introduce small errors.
Edges
It is arguably clearer and more accurate if you mark an edge, because lining up the edge of a stud with a pencil mark is less ambiguous and requires almost no judgement. But to do this you need to use a tiny bit more brainpower because you are not marking 'round' numbers. You will still be marking every 400mm, but with an offset of half a stud width which is about 23.5mm. 400mm minus half a stud width = 376mm, so you would be marking at 376mm, 776mm, 1177mm.... Instead of 400, 800, 1200mm.
Here is a diagram to explain because the above is totally unclear, even to me:
Marking centres
Marking edges
If you mark edges then you may want to also add an 'X' mark or something - this stops you accidentally fixing the stud to the wrong side of the line. Obviously I've never done that ;-)
My method
I was marking the centres of the studs, but then as a second operation I was also going around with a little jig I made to mark both edges of the stud. This took a little bit more time, but it meant that I had error proofed things a bit. I dont have a picture of this so here is an artists rendition:
Yes its just an offcut with the centre marked in sharpie but I'm calling it a jig
Alternative methods if marking 'edges
23.5mm spacer
I suppose you could cut a bit of 4 x 2 in half to give you a 23.5mm spacer and hook the tape over that before hooking it over the edge of the bottom plate, I've never seen anybody do that however so it's probably a terrible idea :-D You would probably have to clamp it in place which means extra faffing, there is probably a reason that nobody does this. Artists rendition below (note the use of an 'X' so you know which side of the line to fix the stud):
Story Stick
You could make a marking stick - or 'story stick' (for example a length of batten) with all the stud placements marked on it - those measurements could easily be transferred to your bottom plate . The only issue I could predict with this would be ensuring it doesn't move once lined up with the edge of the bottom plate - with a tape measure you can keep pulling it tight as you are marking out to check its still aligned perfectly, but with a stick, you never really know if its still lined up at the other end
I guess you could put a lip on the end of the story stick, that would help with error proofing and would also speed things up. Sketch
Nail gun or erm, hammer
I used a nail gun, a green Hikoki (I just hear hokey cokey in my head). I spent a little time trying to decide about this, its £500 for a nail gun and I couldn't figure out if it saved enough time to justify it. Because I was on the fence, it was something quite small that swung the decision for me.... I realised that it isn't just a time saver, its also a functional improvement, its essentially a one handed hammer + nail. This means you can hold a workpiece with one hand and nail with the other - you cant do that with a hammer (making the assumption you have just the two arms). I have no regrets investing, it took me about 30 minutes to build each wall section, which is much quicker than if I had done it manually, but I really like the one handed operation, I can line up the stud with the top / bottom plate and press a button and its fixed, in exactly the place I wanted it.
I feel that gas nail guns are a bit outdated now but they still have their followers. With gas it can be problematic in cold weather, and more importantly for me, you have to keep buying gas - this just seems archaic to me. They are a bit lighter however. Anyway, as far as I know there are only two real options for first fix if you want to avoid gas - Hikoki and Milwaukee, these both work on just a regular cordless battery, and in my experience with the hokey cokey it works flawlessly. Not a single issue in 2850 nails (I have 150 left in the box). Air is the other option I suppose, but then you need a bulky, noisy compressor - way too much faff for me.
Building the walls
Very straight forward, lay all the timber down on the floor, mark out where the studs go, line them up, nail them all in place, stand the wall up. I used either 2 or 3 nails in each stud, depending on how I was feeling, sometimes I was in a 2 nail mood and other times I was in a 3 nail mood. Absolutely no science behind this one at all, I figured that the nails aren't really doing all that much anyway for the walls. (studs are in compression vertically).
Once the wall is upright, use a spirit level to get it plumb in both directions (left/right and front/back) and then fasten diagonal braces in place to keep it fixed in both axes.
Alternative construction method
At this stage, you have to make a decision about how strong you are and how heavy a wall you think you can lift, bearing in mind the embarrassment / annoyance if you go too big and cant lift it :-D Basically, you get more material efficiency and more time efficiency by building either wider walls on the ground, or more complete / complex walls on the ground.
Wide +
If you build them wider then you need less wall sections and less joins and that means one less timber stud per join (and a few less nails / effort too). If you are joining subframes together you also need to think about the spacing as that will throw out your 400mm centres if you dont plan ahead and think about what you are doing - not exactly complex but its an extra thing (or 47mm) to think about, and an extra thing to go wrong.
Wide versus non wide walls
Complex +
If you build them more complex its quicker because doing things flat is easier than doing things upright. This is the reason why we eat our dinners off tables, and not walls :-D What I mean by complex is adding more stages / materials. For example:
- OSB sheathing
- battens for the cladding
- house wrap / vapour barriers.
These can all be attached on the ground when wall is flat. House wrap is a great example... if you think about how easy that is to attach to a wall which is flat on the ground, just roll it out and staple it, 2 or 3 minutes work. Then think about how you might try and do that in vertical position with a 100m roll that weighs 15g - not as straight forward as you might think and could take a few hours to do the full building on your own. So the more you can do when the wall is flat, the better, but you need to be able to lift it. I was working alone so I defined (guessed) my maximum as a 5m wide wall (just the frame, no sheathing or anything else). But if you have access to some additional muscle power (more people) then you should consider adding as many elements as possible before raising it up into position. This 5m width turned out to be about my maximum, I only just managed to shoulder press it up to vertical. My walls are 5 x 2 thick and spaced at 400mm centres so its quite a bit of wood and I'm glad I didn't try and push it any further, like 5.01m for example.
Note: this is a decision you need to know at material ordering stage (do you buy 5m + 4m lengths to get your 9m building width (2 wall sections) or do you buy 3 x 3m lengths (3 wall sections).
Noggin spacing
Noggins stop the studs or joists twisting over time. To fix the noggins to the studs you have two options:
- Place them 'in line' and use toenail fixing method
- Stagger or 'offset' the noggins and allow nailing from the sides
I am not a fan of toe-nailing, I use it when I have to but it feels like a bodge, and if you get the angle and placement wrong it can make a bit of a mess. So I decided to use the staggered method so I could shoot nails in from the side at 90 degrees.
In terms of placement of the noggins (and I have not seen anybody else doing this - oh ohh, we know what that normally means don't we) but... I decided that if you are staggering the noggin placement then you may as well do it with a useful placement. What made sense to me was to have at least one 1200mm aperture (I can't have two because my walls are only 2.1m tall). So you will see from the pictures my really weird looking noggin spacing - maybe it will catch on.... :-D
Anyway, future self has informed me that this spacing has turned out to be a bit of a masterstroke because it's one less PIR cut to make per stud spacing (uncut PIR is 1200mm wide) which means less dust in your eyes and mouth, and also less waste, which = more beer money.
Note: I know that the noggin would logically go in the centre of the stud, and mine are offset, but actually not by that much, only about 200mm, so I do think this is robust enough, certainly once you factor in the PIR + spray foam mega stiffness combo, oh right that's in the future....
opps, I've hit my 10 picture maximum again, I will put the pictures in the next post.
Martin
Like the first time you realise a hand saw has a 90 and 45 degree guide built into the handle....
There are a lot of Duh moments you discover when you are a do it yourselfer. Usually when you are just about done.
