Insulating log cabin floor

richieboy · 10 Jul 2017 at 21:44

New log cabin arriving tomorrow and as I'd like to use it over winter I'm wondering if I should insulate under the floor.

Having a look around it seems people recommend using Celotex board under the floorboards...what are people's thoughts? I know It should be able to breathe under there so not sure if there is a better option? It's on 4" bearers so quite a lot of room...

MassiveJim · 11 Jul 2017 at 13:26

put the celotex inside the cabin.

Derek W · 11 Jul 2017 at 13:29

Plusfloor insulated floor boards. Not going to give you much insulation but will add a bit on top of the current floor. Might be easier than to fiddle about underneath the cabin?

richieboy · 11 Jul 2017 at 14:58

Cabins not in yet so nice and easy to access at the moment- problem if I put the celotex inside is it raises the floor too much...is there a reason I shouldn't put thme under? Here's an example picture of someone doing what I am thinking:

...and the lovely 28mm thick floorboards I have go on top...

the_r_sole · 11 Jul 2017 at 15:40

That looks like it's going to be draughty! If you do go down that route be sure to cut the boards tight and fill in the gaps...
A lot depends on what the construction is going to be, is it 100mm before the bottom of the floor joists? (i.e. you can achieve 100mm air space under the insulation?
I'm guessing that stopping draughts in the floor is more important than insulation for something like this, insulation in the roof/walls/windows/doors will be more effective...

snappyfish · 12 Jul 2017 at 09:13

Interested also, have an LV low clock house arriving today, have been told to use 50mm Celotex under floor boards.

MassiveJim · 12 Jul 2017 at 14:40

richieboy said:
Cabins not in yet so nice and easy to access at the moment- problem if I put the celotex inside is it raises the floor too much...is there a reason I shouldn't put thme under? Here's an example picture of someone doing what I am thinking:

...and the lovely 28mm thick floorboards I have go on top...

Personally I wouldn't want my insulation exposed to the elements.

Define "too much"

danza · 12 Jul 2017 at 20:11

When I did mine, I laid down DPM (effectively made a tub in the footprint of the cabin), then the floor bearers and then laid Celotex between them as pictured above. I used 50mm as my bearers were 50mm square section. Mine's been in for about a year and it's doing great.

I'd show pictures, but photobucket are being massive bellends and have banned third party hosting unless users pay fees.

MassiveJim · 13 Jul 2017 at 13:01

danza said:
When I did mine, I laid down DPM (effectively made a tub in the footprint of the cabin), then the floor bearers and then laid Celotex between them as pictured above. I used 50mm as my bearers were 50mm square section. Mine's been in for about a year and it's doing great.

I'd show pictures, but photobucket are being massive bellends and have banned third party hosting unless users pay fees.

This way is ok because you "encased" the insulation in DPM.

However it won't allow any airflow under the shed will it ?
You need airflow to stop damp etc.

snappyfish · 13 Jul 2017 at 23:49

What did you do in the end?

clubb699 · 15 Jul 2017 at 19:46

I did the floor and the roof heat rises

i used plastic pvc thats used for house facia the cladding looking stuff that fits together , its covered the roof to hide the 50 mm kingspan it looks lovely and holds in the heat great .

snappyfish · 15 Jul 2017 at 20:03

clubb699 said:
I did the floor and the roof heat rises i used plastic pvc thats used for house facia the cladding looking stuff that fits together , its covered the roof to hide the 50 mm kingspan it looks lovely and holds in the heat great .

so what size did you use in floor? having a similiar issues my bearers are 50mm then hits concrete..

clubb699 · 16 Jul 2017 at 12:18

snappyfish said:
so what size did you use in floor? having a similiar issues my bearers are 50mm then hits concrete..

I put dpm down then placed the 50 mm coltex /kingspan with 50 mm battons every 400 mm ish, then lay the tongue and groove floor down they supplied and on top of that underlay and carpet.