Kingspan Warm Roof?

[Zeberdee]

Hi,

Am I right in thinking a warm roof is constructed by installing the Kingspan TR31 directly on top of the joists and then the waterproofing??

I may be doing a job where the bloke wants plyboard decking on the joists 1st and then the Kingspan TR31 put on top of that and then waterproofing

This is a new build so surely installing the Kingspan 1st would be the best option? I've heard of Kinspan going over exsisting felt or decking on an old roof, if all decking was sound.

Cheers

Tony.

 

[noseall]

So long as the insulation is positioned above the joists then it it usually acceptable. The importance of the insulation position regards a 'warm' roof is that it is positioned above the rafters or joists.

Many insulation manufacturers will guarantee their products even if they are used in 'sandwich' with other materials such as plywood or existing felt coverings.

 

[Zeberdee]

Thanks for the reply...

So it'll be alright to put plyboard on top of the joists and then fix the Kingspan TR31 on top of the new ply? The Kingspan TR31 has the 6mm ply already bonded on, So it seems a waste of time decking and then insulating when the Kingspan TR31 board come all in one.

Ive also read a Non-Setting mastic is to be put onto all joists wher the Kingspan boards are butted to maintain the vapour control?

Where do you get this from? I've had no look searching on the net.

Cheers

Tony.

 

[noseall]

So it'll be alright to put plyboard on top of the joists and then fix the Kingspan TR31 on top of the new ply?

Highly likely yes, but as you say a ply bonded sheet does not necessarily need another layer beneath.

Ive also read a Non-Setting mastic is to be put onto all joists where the Kingspan boards are butted to maintain the vapour control?

True. All joints must be sealed. As for non-setting mastic - just use silicon or similar as i can't see the need for an oil based mastic other than the fact it will deal with movement a little better.

 

[freddiemercurystwin]

So it'll be alright to put plyboard on top of the joists and then fix the Kingspan TR31 on top of the new ply?

I'm not aware of a requirement for ply to be placed between the joists and insul.