Flat roof cold deck to warm deck EPDM advise

[bosyuk]

I've currently got a flat roof over an extension thats got cold deck insulation with vents in the soffits. I want to convert to warm deck, renew the felt with EPDM and get new fascias and soffits at the same time.

I'm thinking of going with something like Kingspan Theramroof TR21 build right up as thick as possible but at least 100 mm.

Do I have to remove all the insulation thats currently in between the joists before adding the warm deck as the new soffits wont be ventilated and could result in condensation problems?



Also as you can see in the picture the extra height of the insulation is going to cause problems as it reaches the tiles. Any ideas on getting round this?

Thanks.

 

[noseall]

Do I have to remove all the insulation thats currently in between the joists before adding the warm deck as the new soffits wont be ventilated and could result in condensation problems

Yes, remove all the insulation betwixt the joists.

Also as you can see in the picture the extra height of the insulation is going to cause problems as it reaches the tiles. Any ideas on getting round this?

You will need to remove the bottom course in any case in order to fit an 18mm ply lay-board. You can the probably close up the gauge on the final course or remove both courses and close the gauge on em both.

You will also need to lay a cocking fillet along the lay board as to provide a 'kicker' for the bottom tile. This is best fitted prior to covering as then it becomes protected from the wet. Some bodgers simply slide a roofing batten under after the roofing material has been applied but they usually rot away.

 

[bosyuk]

Thanks for the reply.

 

[Deluks]

Depending on insulation type and condition, you could push all the old insulation tight up against the new covering, this would give an overall thicker 'between & over' layer of insulation. It could also mean you wouldn't need as much insulation on top, saving cash/space.