Battening and insulating the walls

I spent yesterday and today battening the internal walls. The first step was to effectively wrap the walls in a breathable membrane. This would help to prevent condensation forming, however it shouldn't be an issue as I'm using the same 'warm' method used for the ceiling. This will mean there is no air around the wall, thus condensation can not form. To be on the safe side though, the insulation will be sealed in with silver foil tape, preventing any form of air movement.

Once the membrane was up, I started on the stud work.

To get the correct widths, I cut a sheet of Celotex in two lengthways, creating a 600mm width (or near enough to 600mm as the sheets are ever so slightly smaller than that), and basically used it as a guide as to the distance between battens.

Once the vertical battens were in place, I placed a single noggin across the middle of each. 

The same was done for the back wall, the only difference being that smaller gaps were used between the vertical supports. 

For the left hand wall, I opted to use two sets of noggins as this wall will likely have a cupboard on the wall, in addition to monitors mounted on it. Because of this, I've basically strengthened a few parts of it to allow for heavy loads to be supported. 

I've opted not to add the insulation to this wall just yet as the electrics need to be added. I've also not yet sealed the insulation in place yet as I'm waiting for some more silver foil tape to be delivered (damn you eBay!).

Once the walls are sealed up, I'll get the right and back wall covered in plasterboard.

At this point you may notice I'v not talked about the 'front' wall (I.E the wall with the door and window). I had a bit of a problem with this one. The door and window that came with the shed have a 1.5cm frame built into them. The floor bearer does not. Meaning that the roof bearer is 1.5cm out. So I basically need to add a 1.5cm piece of wood across the top, to support the plasterboard. I've actually got a ton of spares from the shed build so hopefully I can find something half decent to use for this. Once that's done I can get that wall insulated and boarded up. Thankfully there will be no major weight load on this wall, just plasterboard, otherwise it could have cause a potentially annoying problem resulting in an odd shaped wall.

Finally, taking the idea from someone else who is currently converting a shed (whom I met via the DiyNot.com forums), I've decided to add a 'lessons learnt' section to each post, basically saying what I screwed up or would do differently next time, so here it is:

Lessons Learnt

1. Never underestimate the amount of wood and screws you'll need. I did three separate trips back to Wickes to get more supplies!
2. A staple gun is very helpful when putting up a breathable membrane. You still need to seal it to the wall with a waterproof tape (I opted for duct tape) but it helps hold it in place while you get it all lined up.
3. Cutting Celotex is a pain. If using a saw, get one with extremely fine teeth. I found a kitchen knife (The kind they use in Subway to cut sandwiches - very sharp!) to generate zero dust, compared to a saw, which got it everywhere!

Photos

The full set of photos so far can be found on the Flickr Page.

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The end does seem to be in sight. The main big jobs remaining as of this post are:

• Seal the insulation on the right and rear wall
• Sort out the 1.5cm gap on the front wall, and add insulation
• Plasterboard over the front, right and back wall
• Get the electrics fitted on the left wall
• Insulate (and seal) the left wall
• Plasterboard the right wall
• Skim over the plasterboard gaps
• Paint the room
• Add the flooring
• Add a skirting board
• Move in!

Actually, when you put it into a list, there is still a hell of a lot to get done. My feeling is that once the electrics are in place I'll be finished in no time. However while I'm waiting for the electrics to be done, I can still get the three other walls finished.

One thing I also want to do at a later stage is add a seal around the roof. I noticed that the roof edging boards do have a very tiny gap, meaning water can trickle under them. It would never get into the shed as its on the overlap, however I've bought a bitumen sealant that is designed to fill gaps around fascias. I'll likely also add some extra sealant on the joins of the roof felt just to make me feel that bit happier about it being water tight.

Ceiling Done!

I (well...we) got the plasterboard up on the ceiling today...what a hellish task that was! Couldn't believe how hard it was to get it to go up, but got there in the end. The shear weight of the boards combined with the fact that we had to get them to fit perfectly made it a tiring task.

I've also modified my plans slightly. To speed up the process, I've opted to just go for 3 double sockets on one wall, and nothing on the other 3 walls. This means I can get three walls completely insulated and plasterboarded and then get the electrician to work his magic on the final wall. I was originally planning on four double sockets (2 on each of the 12ft walls) however I really don't think I'll need it, and can always use an extension lead if I need more.

I also opted not to have a ceiling light as I've previously found that you can get away with a cheap-ish Ikea up-light in the corner. I'll then top it off with a couple of desk lamps, these will all use a strong white light bulb instead of a standard yellow-ish bulb. This should help a lot as I'll obviously be using the room as an office, so want a very crisp, clear light in there.

I've not got photos of the plasterboard up yet as it started pissing it down with rain just as I finished.

One really annoying thing I found was that because of the odd spacing on the roof batters, we had to cut the plasterboard in odd places to get it properly supported. We then had to add the top of the wall supports just under the plasterboard to give it extra support around the edges. In all it took about 2 and a half hours. Once the room is pretty much finished, I'll add joining tape and then skim over the gaps. I'll then probably line both the walls and ceiling in a thick lining paper before painting.

Next on the list is getting the wall studs in place, weather permitting, I should be doing it tomorrow.

Insulating the roof

When it came to the roof insulation, my original plan was to use 100mm Celotex, and have a 50mm air gap above, creating whats known as a 'Cold Roof'. Soffit vents would then be placed at each side of the shed, to allow airflow on the upper side of the celotex, preventing condensation.

BUT. I messed up. I went to fit the 100mm celotex, to find my rafters were only giving me 120mm gap, meaning my air gap could only be 20mm, which would not be enough.

Because of this I opted for a kind of 'hybrid warm roof'. A breathable membrane is attached to the roof from the inside, coating it completely. The 100mm celotex is then placed between the rafters. At this point there will be little to no gap between the Celotex and the plasterboard that'll be added later.

I sealed up any gaps with expanding foam, and used Celotex Foil Tape to completely seal the gaps around the celotex. This means no air can get above the celotex, thus there should be no condensation.


The only downside to this method is that an air vent has to be placed somewhere inside the shed to avoid condensation building up on the ceiling. I'll likely place a small vent above the window or door, assuming I can find one that is small enough.

If this was a house build, this method would probably not work, however since its a one room shed conversion, it shouldn't cause any problems with thermal bridging so long as sufficient ventilation exists inside the room.

So far I've got the celotex up and secured, I've now just got to place the plasterboard on the ceiling and can then make a start on the stud work walls.

I had to wait until now to start the stud work as the building has a sloped roof, and it would have been near impossible to work out how high each wall joist needed to be without having the roof completely finished.

Once I have the studs in place, I'll be calling an electrician in to get the power fitted, as I assume this will need to be done before I add wall insulation.

The end is in sight...weather permitting I should be able to get the stud work done over the next week. That being said, given the weather over the previous few days I'm pretty doubtful. I came very close to going out and buying one of those white plastic gazebos so I could continue working!

Insulating the floor

For the floor I opted to use 50mm Celotex PIR board. This should provide a decent level of insulation underfoot.

I started by lining the floor (Which was basically the HawkLok shed base, and the floor rafters) in a damp-proof sheet. Basically this is just a very thick black plastic sheet. It covered the floor completely, and will stop any water from under the shed damaging the insulation.

The Celotex was laid between the rafters. To cut the Celotex up I used a standard saw, however a kitchen knife or knife with a vert fine set of teeth will be better, and leave much less dust - never, ever cut Celotex up without an asbestos-grade face mask. It's not in any way cancerous, but it will cause breathing problems for a couple of days, and from my research it turns out that the cheap paper masks dont actually do bugger all, so make sure its asbestos grade (they are around £5 each).

Once the insulation was fitted, any gaps were filled with expanding foam. I didn't need to worry about using foil tape around the edges as the celotex was on the sealed plastic sheet, so no air or liquid restriction was needed.


The floorboards were then laid from front to back, they interlock a bit like laminate flooring but are made of solid wood. They are then nailed down to the rafters.

I was actually pleasantly surprised at how stable the floor was. I expected a bit of 'bounce' to it, but it was pretty rock solid.

Once the floor was done, it was time to work on the ceiling, which I'll cover in the next post!