Posted: Thu Mar 26, 2015 5:02 pm I am as sick as ****! I set out to do my roof felting a week ago when we had a day of decent weather. First job was to put the underlay felt down. It all went down well, I smoothed it all down as I secured it, with about a million clout nails and the end result was nice and flat underlay. I was set to put the top sheet on the following day (cold adhesive) Unfortunately since then the weather has been either wet, too cold or very windy. Now after inspection I have noticed that there are lots of big air pockets and creases in the underlay grrrrrrrrrrr!!! How did they get there and do I now have to rip up and start again? Thanks
Mmmm interesting, why that's done that???? Got to ask though, why have you laid it top to bottom, as opposed too side to side, the object is to make the roof waterproof, no.!!!!!
Hi, Not sure what you mean? The slope is along the long side. It's lowest point is at the left side near the other shed and the highest point on the right near the fence. I have laid it across the slope as you are meant to do..
Would say that your roof has contracted at a different rate to the felt and you see the results. Did you have the felt outside for a while before you fitted it to let it get to outside temperatures? Was the sun on the roof when you fitted it?
Hi, Yes it was a lovely sunny day when I laid it, but then (being March) the temperature plummeted at night and we have had poor weather since. The felt had been stood upright in my garden for about a week and prior to fitting it I cut the widths and had them laid out for a couple of hours. The roof is made up of 28mm thick T&G planks, running from the front of the cabin to the back (90 degrees to the length) another thing I don't get is it is much worse on the right hand side than the lower left hand side for some reason?? (more airflow underneath on the left perhaps??) thanks
What is well spotted? I am confused the felt has been laid 90 degrees to the slope (across the slope) as it should be with the bottom strip being overlaid by the one above it.
Would have thought it would have gone from left (1) to right (6)...But don't worry about it, just an observation, nice summer room...
oh I see, laid lengthways. I was always under the impression it should be laid across the flow of water!. thanks, just very peeved about this current development
I think that happens regardless, as I've sent that many a time, its not the green mineral stuff is it, which I think is quite thick? B J
I gotta say the pic does make it look as if the roof slopes the opposite way, the shed on the left roof is causing an optical illusion.
Further to CraigMcK's post and OP's reply... It being fitted on a lovely sunny day, but then the temperature plummeted at night... Contraction & Expansion... The right hand side above the enclosed space of the shed being subject to the build up of heat inside, whereas the roof above the open area on the left remained cooler and therefore expanded to a lesser degree. Once the felt was nailed and the temperature dropped, the T&G roof will have contracted causing the felt to form the varying severity of wrinkles. I'd imagine the ideal conditions would be a dry but cloudy day, avoiding both extremes of temperature and therefore hopefully finding the middle ground in terms of expansion & contraction. Cross me fingers and hope the felt had the flexibility and tolerances to cope with the roofs inevitable movement. Personally I'd opt for a single sheet of EPDM, job done in a hour and more than likely to outlive the shed.
Interesting reply - thanks!! Does that mean in the warm weather it will flatten out again? He hopes!!
Most welcome! Given a day with the right humidity/temperature and it being thin underlay felt it will undoubtedly flatten out from its current state, t'is also most likely the heavier, thicker mineral felt will compress any remaining minor creases and result in an acceptable watertight roof covering. Given that you've already forked out for the felt & adhesive I'd crack on with your original plan, but with the intention of sticking a sheet of EPDM on it when it needs replacing.
It’s an optical illusion alright. Slopes in picture right to left not top to bottom as I originally thought