Insulating under cabin floor

[NSS]

Building a 'log cabin' in the garden and, having laid the bearers today I'm debating whether to add some under floor insulation. Should be a doddle to fit between the bearers as they're raised on brick padstones (see pic). Question is what (Celotex/Ecotherm/etc) and where to buy cheaply? Only need 3 off 2400 x 1200 x 70mm sheets.

 

 

[Onoff]

Some pillock I know did his shed floor with spray foam can you believe!

 

 

[Ferdinand]

Somebody's offcuts?

 

Or one roll of rockwool or similar.

[NSS]

6 hours ago, Ferdinand said:

Somebody's offcuts?

 

Or one roll of rockwool or similar.

Thanks, but need to do it this week so offcuts are probably not an option, and not sure I want all sorts of insects nesting in rockwool or the like.

[Barney12]

Jablite jabfloor? 50 or 70mm is relatively cheap. Available in 2400x1200 sheets for around £14 including VAT.

 

its what I used to insulate my shed and workshop floors and is surprisingly effective. 

[scottishjohn]

only problem might be it wants to fall out.

 make a ledge with tile baton on the floor beams for insulation to sit on ?

[Onoff]

19 minutes ago, scottishjohn said:

only problem might be it wants to fall out.

 make a ledge with tile baton on the floor beams for insulation to sit on ?

 

Or staple some st/st mig wire from one side to the other underneath so the eps/pir sits on that.

 

Need to stop "things" getting underneath and setting up home too.

[epsilonGreedy]

1 minute ago, Onoff said:

Need to stop "things" getting underneath and setting up home too.

 

 

Yup, make sure you don't create the neighbourhood Rat Hotel.

[Onoff]

4 minutes ago, epsilonGreedy said:

 

Yup, make sure you don't create the neighbourhood Rat Hotel.

 

Aluminium sheet maybe around the bottom?

[PeterW]

4 minutes ago, Onoff said:

 

Or staple some st/st mig wire from one side to the other underneath so the eps/pir sits on that.

 

Need to stop "things" getting underneath and setting up home too.

I’d fill the whole of the base less 10mm with sharp 20mm gravel, it will drain but won’t provide a “home” for anything. Then use 50mm jablite on battens and it will keep it “warm enough”. 

 

Other option would be to get some big bags of vermiculite and mix it 10:1 with OPC and a little water and pack it between the joists. It will have a fair insulation value if you don’t pack it too much, but will probably be better than having an air gap. 

[Ferdinand]

Hmmm. Leca might do it. But I think that is more expensive.

Edited April 23, 2019 by Ferdinand

[Onoff]

A bed of crushed broken glass would dissuade "things"!

[NSS]

There'll be no danger of rats or the like getting under it, and the bricks on which the bearers sit provide a convenient 'lip' to sit the boards on so no need for supporting battens/wire either. It will get damp under there though so main concern is for something that won't absorb moisture and then 'droop'.

[Jeremy Harris]

EPS (a.k.a Jablite) would seem to be relatively cheap, moisture resistant and easy to cut to fit.  A squirt of low expansion can foam around the edges would hold it securely into the timber floor framing, although it looks as if it might be OK just resting on the brick ledges.

[Barney12]

You could actually lay the jablite straight over the top and then screw your floor down to the joists creating an EPS sandwich. The jabfloor stuff has an impressive compression strength. 

[NSS]

4 hours ago, Barney12 said:

You could actually lay the jablite straight over the top and then screw your floor down to the joists creating an EPS sandwich. The jabfloor stuff has an impressive compression strength. 

Except that would make the floor higher than the door threshold ?

[Barney12]

9 hours ago, NSS said:

Except that would make the floor higher than the door threshold ?

 

Sorry I assumed this was being hand cut to bespoke specifications. Hadn’t realised you were cheating with a flat pack ??

[Onoff]

9 hours ago, NSS said:

Except that would make the floor higher than the door threshold ?

 

Could you not add a batten the depth of the proposed insulation, around the base frame perimeter now, to account for this?

[NSS]

27 minutes ago, Onoff said:

 

Could you not add a batten the depth of the proposed insulation, around the base frame perimeter now, to account for this?

Not really as the bearers are set low so as to minimise the threshold height to make wheelchair access as easy as possible.

[daiking]

Can't help on the insulation front but watching with interest. What's the size and spacing of members? They look like 2x4s?

[NSS]

20 minutes ago, daiking said:

Can't help on the insulation front but watching with interest. What's the size and spacing of members? They look like 2x4s?

The bearers are 70 x 45mm (doubled up at front and rear edges) spaced at circa 470mm centres.

[daiking]

13 minutes ago, NSS said:

The bearers are 70 x 45mm (doubled up at front and rear edges) spaced at circa 470mm centres.

 

Cheers, what’s the overall size of the building?

[NSS]

35 minutes ago, daiking said:

 

Cheers, what’s the overall size of the building?

It's this one...

https://www.simplylogcabins.co.uk/norland-newark-1-log-cabin-p573