Expansion Gap?

[phil p]

Could I ask some advice please.

I'm busy insulating my garage at the moment and Ive started boarding it with 12mm plywood sheets.

I have only put 3 sheets up at the moment and just thought, should I leave a few milimetres expansion gap inbetween sheets?

The board are decent quality, Ive used some in the past and some of the offcuts have been left outside for the last year or so and they don't seemed to expanded, split or peeled.

As I say Ive only just started so I could easily loosen them off and leave a gap.

What do you guys think?


Thanks

 

[Bradshaw Joinery]

I wouldnt worry too much with plywood in that direction,
Its not sitting againts a very damp surface at all is it?

 

[longinthetooth]

Ply - pretty stable. Particle board a different matter. For the long-term health of the structure, are you installing a vapour barrier?

 

[phil p]

Hmm!

Now hoping I have done this right!

Haven't used a vapour barrier as Ive read a few posts, some people say "yes", and some "no", and there have been a few discussions as to what side you put it, so I opted for the "no" option.

What I have done is built the framework, kept it an inch off the wall (pre fabricated garage) and put some damp proof membrane underneath the frame on the concrete floor.

Filled the framework with 2 inch Celotex and now lining with half inch ply.

If this is drastically wrong I suppose I still have time to sort it, however I'm loathe to do it as Ive silver taped all the insulation into the framework and really spent time framing and lining it.

Cost a fortune aswell, spent more on the insulation, timber for framing and plywood than what I paid for the garage!

Is this O.K......please say "yes"

Think I would only dismantle if there was very serious issues.

Phil

 

[MickCheese]

I am of the opinion that if you were to use a vapour barrier then it should be own the warm side, so just under the ply.

Mick

 

[kostello]

I think the foil on the celotex is classified as a vapour barrier

 

[G S Haydon]

For a garage your fine on all counts. Rest easy and don't take it to bits. Wouldn't stress about leaving a gap in this context, ply is quite stable.

 

[No skills]

No gap, our ply lined boxes get exposed to all sorts of temperature and moisture variations and we havent had any problems - a 40' would have roughly 9 and 1/2 sheets in a row, you would expect that sort of run to show up any problems over time.

HTH

 

[longinthetooth]

MickCheese above has the right principle. Is the gge a heated space in its own right - or does it abut, & borrow heat from, the house?

Is the insul between studs or rafters or laid over? I ddn't want to be alarmist, but now wld be the time!