Shed Revamp

[Mark A]

I've started to fix my shed to make it slightly more comfortable this winter. I took the roof off last weekend, cleaned it up and put it back on with big tek screws and StixAll, so the leaks are now sorted.

Stage 2 is the floor. Currently the shed is fixed to some 3x2s,which are resting on a concrete base with a tarpaulin between. I'm planning to replace the old 3x2s with a 6x2s, then use 4x2s for the floor joists.

Here's a sketch up drawing of what I mean

First question: Do I need to incorporate some sort of ventilation? There will be a 2" gap between the DPM and the joists, so do I need to cut notches/ drill holes in the 6x2's so damp air can escape or will it be ok?

Second question: What type of insulation will be best (and cheapest) to go between the joists? I'm guessing it's polystyrene but would fibre glass loft insulation work too if I held it in place securely?

Thanks,
Mark

 

[jack55]

Hi, you can get 70mm round sofit vents, which if you bore holes in the 6x2 and fit them in with a bit of mesh inside to stop any mice getting in. I used 50mm polystyrene for my floor. laid it on 18mm chip board t&g then the polystyrene then another layer of 18 mm chip board. Worked a treat, with the wall and roof insulation its nice and warm without a great deal of heat input.

 

[bosshogg]

Mark...I don't like starting with a question when you've gone too lengths in both your description and sketch, but why do you want the joists lifted from the ground as that will promote vibration in the joists?
That being said, I would advise either renewing or retaining, unless there is some rot, the 4"x2" trimmers along with the 4"x2" joists, perhaps replace the tarpaulin with 4" dpc, the bare concrete will be protected by the shed and allow any moisture which is /could be present, to seep away. Now if you take out a few 10mm deep rebates, full width, along the top edge of the trimmers, staple on a bit of fly screen to the inner faces, you will have a more vibration proof/load bearing, ventilated shed floor, which if you choose can also be insulated between joists/sleepers...bosshogg

 

[Mark A]

I was going to raise up the joists as the concrete base isn't level or flat at all, then add additional supports to prevent the floor flexing and bouncing too much.

To be honest, I can't remember what the ground is like under the shed as it's made from a mixture of waste building materials bonded together with the excess screed from the house. I may need to fill in the dips if water collects in them when it rains. It was only meant to be a temporary position for the shed so we mistakenly didn't give too much attention to damp proofing etc. Next time I know :roll:

Thanks,
Mark

 

[bosshogg]

I would suggest a sand and cement levelling screed, bonded to the existing concrete with a pva slurry, this would give you a flat base to level out shed floor. sheets of slate can be used to set out levels throughout the concrete base, then infill between with the screed. You can then preceded with the dpc and other prior suggestions, if you want...bosshogg

 

[Mark A]

Thanks bosshogg

I'll see what the base is like first, because if it's not too bad I might just buy some rapid setting cement / postcrete to patch up the hollows. Otherwise it'll be a long job and I have to empty the shed into my gazebo "extension" to get to the floor and no doubt it'll be raining! I might do it this weekend if the forecast appears to be ok. It'll still rain though...

Cheers,
Mark