External Insulated shed roof build up

[daiking]

The detail on this is a bit

sketchy. You put your

sheet insulation on top of the roof boards and then your roof material on top of that and fix through. Simples.
 

The log cabin roof is 18mm tongue and groove timber planks, my insulation is 50mm PIR and my roof material (first time round) is some thick felt and I don’t have anything for a top wooden deck on the insulation.

 

the cabin is a modern design, the roof is very flat with a tall fascia surrounding it. 
 

So, can I get away with fixing the felt to the wood with nails on the side overhangs but across the top of the roof just gluing the joints of the felt overlap with a tube roof/gutter seal and not attached to the insulation?

 

To stop the felt from lifting (unlikely) I could lay battens over the felt,  secured to the inside of the fascia structure.

 

Its just that the roof felt was free with the cabin and I only intend to put a proper epdm  roof on it in a few years when I shall sort it all properly, probably an OSB deck to fix through the PIR and glue the epdm to.

 

(then there’s the wierd fascia board internal timber detail that gets in the way of the insulation that I need to work around)

Edited March 31, 2021 by daiking

[Onoff]

7 hours ago, daiking said:

tube roof/gutter seal

 

No! Depending on the "free" felt you want proper felt adhesive imho even more so if your just laying it on.

 

Is it just one layer of felt supplied? Got a spec for the felt, photo maybe? Traditionally a decent felt roof would have 3 layers on a domestic say extension and a decent shed roof two layers. 

 

I did two layers on my shed roof. 1st layer of just sand felt bonded and nailed. Second layer green mineral bonded to the first. I took particular care bonding the joints. I kept some clean sand/green mineral sweepings that come of the felt and sprinkled these over any dribbles at the laps. I've no lathes or anything holding it down, Hell I've not even finished the fascia boards or gutters! ?

 

I used Wickes felt adhesive.

 

 

 

Roof still looks like new pics from 2017 apparently. I might knock this down soon / extend it. 

 

 

 

Edited April 1, 2021 by Onoff

[daiking]

1 hour ago, Onoff said:

 

No! Depending on the "free" felt you want proper felt adhesive imho even more so if your just laying it on.

 

Is it just one layer of felt supplied? Got a spec for the felt, photo maybe? Traditionally a decent felt roof would have 3 layers on a domestic say extension and a decent shed roof two layers. 

 

I did two layers on my shed roof. 1st layer of just sand felt bonded and nailed. Second layer green mineral bonded to the first. I took particular care bonding the joints. I kept some clean sand/green mineral sweepings that come of the felt and sprinkled these over any dribbles at the laps. I've no lathes or anything holding it down, Hell I've not even finished the fascia boards or gutters! ?

 

I used Wickes felt adhesive.

 

 

 

Roof still looks like new pics from 2017 apparently. I might knock this down soon / extend it. 

 

 

 

I’d be quite happy to get a tin of cold felt adhesive and use that - I’ve run out after doing the playhouse and shed many times.
 

The felt is a wierd one it’s some IKO stuff you use  to make the valleys and hip things when you use shingles. Looks/feels very different to the shed felt they do.

 

I just don’t want to stick it to the insulation.

 

“iko armour valley”

 

https://www.iko.be/sites/default/files/valleys uk.pdf

Edited April 1, 2021 by daiking

[daiking]

Ok, “free” is perhaps confusing. It is the felt the cabin manufacturer provides. At the time there was no discount if you upgraded to epdm, hence I took the get now for no cost and will buy epdm in the future (and fit an OSB deck for that)

 

I’m saying this roof is a bit flat but the fall is only 1:120! What’s that? 4.8 degrees? (  tan A = 1/120, so A = tan-1 (1/120)  )

 

it falls 40mm in height over the 4800mm front to back.

 

In a proper installation this felt does have a proper under layer but nothing like that is provided. It’s just felt and you stick it on till it fails. 
 

There are 6 rolls, 40+ sq m, for a 23sq m roof so there is plenty to overlap but I wouldn’t double this stuff up, it’s so thick.

Edited April 1, 2021 by daiking

[daiking]

Still none the wiser as to how the roof should quite be done as tuin never got back to me. 
 

Im also very close to my max height so I may have to amend the design anyway. 
 

it will be tricky to incorporate the weather boards, this perimeter batten and insulation and stay under 2.5m without creating depressions on the roof that will fill with water.

[daiking]

Whose stupid idea was this? No wonder the clowns have stopped supplying felt with this model. 
 

Admittedly it would have worked a bit better had I been nailing it to the roof boards. Without it, the laps just don’t sit down.

[joe90]

On 05/04/2021 at 08:58, daiking said:

and stay under 2.5m 

Don’t stress about the height, no one will come round and measure it. Why not bite the bullet and get your epdm and do it properly from day one?

Edited April 8, 2021 by joe90

[daiking]

37 minutes ago, joe90 said:

Don’t stress about the height, no one will come round and measure it. Why not bite the bullet and get your epdm and do it properly from day one?

I’m definitely expecting a PD complaint at some stage as I back onto about 10 different houses. Chance are high and the least I can do is actually meet the rules. 
 

For the roof, I’ll get some boards for a deck when I order my decking structure and look at it in a few weeks. Will fill the joints as best I can for the time being. I have a spare 80sq m of DPM to put on top if I need to.