Our project at the moment

[Macpherson]

On 08/08/2020 at 20:05, gobbypunk said:

Bloody Shed ,so I decided to glue the roofing felt on got the glue given sticky black shit one side went ok but the 2nd the felt went like squidgy I dont know if its the heat but had to ŕedo one side never had roofing felt go like that before 

Hi, I recon you used bitumen paint which melts the felt...what you need is roofing felt adhesive, they both kinda look the same but they ain't.. I learnt that the hard way too, cheers.

 

Just noticed this was months ago, so you prob know this by now.

Edited December 24, 2020 by Macpherson

[gobbypunk]

No defo used the felt glue it was just the heat I spoke to a few people who said they had had similar problems ,but thanks

[Doug Tait]

I like seeing your work gobbypunk, some lovely work that you do.

 

For the roof have you ever tried torch on felt?

[Jack.P]

Also had problems with the same felt glue 

seemed as though I was sold duff old stock which never  dried so ended up nailing it .

right pain as-well to wash that gunk off .almost as bad as underseal

 

 

[gobbypunk]

Thanks Doug ,I dont think I will do a felt roof again ,it will have to be box profile so much better

[Macpherson]

38 minutes ago, gobbypunk said:

I dont think I will do a felt roof again ,it will have to be box profile so much better

Even if your doing a metal roof you really want to put felt or similar under it to provide a waterproof barrier that stops condensation getting to whatever your fixing onto, I usually use OSB / sterling board but it will swell quite a lot if it 's continually getting damp, cheers and seasons greetings.

[openspaceman]

17 hours ago, Macpherson said:

Even if your doing a metal roof you really want to put felt or similar under it to provide a waterproof barrier that stops condensation getting to whatever your fixing onto, I usually use OSB / sterling board but it will swell quite a lot if it 's continually getting damp, cheers and seasons greetings.

The issue is much the same as insulating shipping containers; profiled or corrugated steel roofing is a near non existent  insulator so the under surface gets cold, worse is that the exterior surface is off the ground and a good radiator, so gets even colder than most of the surroundings. The covered area often contains warmer air than the roof. As warm air holds more moisture than cold air as it meets the cold surface it gives up water to the steel even if the ambient air is above its dew point.

 

So any insulation under the steel needs to be impermeable to air, else the air moving through it gets colder and condenses out in the insulation. Sometimes a thin cloth layer can be used to wick the moisture away or a tyvek layer can be used to prevent the moisture dripping back down and as the roof warms up the next day the water evaporates.

 

When I built my shed I used a profiled steel with 30mm of foam insulation bonded to it, which also has the advantage of not getting scorching hot in the summer.

[andy cobb]

You should look at epdm roofs, basically its 1.2mm innertube rubber. Its glued down in 1 piece with a water based adheasive and contact adheasive around the perimeter.

Theres all types of trims from kerb to gutter edge and it leaves a tidy finish with a life expectancy of 25 yrs +.

We use it a lot for flat and low pitched roofs as it's so user friendly and can be completed in nearly all weathers.

It's obviously a lot more expensive than standard felt, but on a nice product like your shed or a summer house, it's probably worth it

[Efail Fach]

We used EPDM on our 48' x 18' cabin. It was quite expensive (about £1600 inc VAT) & very heavy but seems to be perfect. Very easy to lay once you get it up there. Some say, not the people who sold it to us, it may last 50 yrs.