Roof problems?

Hi,

When I moved into my house about 3 years ago I noticed a couple of the roof boards had came away (don't know what they are called, you have the slates on the outside then the felt then whatever it is the felt is stuck to).

After the rotten few weeks we've had with snow I went up the loft to check everything was ok and nearly all these boards are now hanging off. Could somebody please look at the pictures i've uploaded and let me know if this is something I should be worried about?

At a couple of the places the felt under the boards is sagging (picture2), but most of it looks ok (like picture3).

Pic1
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Pic2
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Pic3
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Hello, the photos appear to show an insulation board of some type such as tentex board. It also looks as if it was fitted after the roof was erected, probably by the former occupieres of the property. This type of board will suffer from sagging and will fall out as you can see, and it does look as if it has been simply wedged into place. The first shot does seem to show some water staining which may indicate a small leak or it may be wind has blown rain up under the felt.
Don't worry to much about the felt sagging either, it does this anyway as a result of heat from the sun warming the roof.The felt will still do it's job if it is sagging. The only thing to worry about is if there are holes and even this isn't the end of the world, indeed my house dosen't even have roof felt.
edit
I've just looked again a the second picture and it does look as if the felt has been fitted wrong. Maybe it's a trick of the photo but is the uppermost peice lapping on the inside of the lower piece inside?

quite a common board used in new builds in the 60s and 70s north of the border.
the boards were fitted to the exterior during construction.
what you are seeing is caused by condensation in your attic, the sheets are very absorbent and susceptible to moisture which has caused them to buckle under the weight of the absorbed moisture.

its worse looking than it actually is and wont make any difference to the integrity of your roof.

you should look at ventilation issues within your roofspace ie soffit, ridge and tile vents. also insulation.

Thanks for the reply's, very helpful.

The water staining wasn't on the boards until the recent snow, and its only directly above the bathroom, there is no insulation above the bathroom as the bathroom as recessed hallogen lights which have a load of electrical connections in the loft, i'm going to replace these so I can get some insulation on there.

It's hard to tell if I have condensation problems in the loft, there are a lot of air holes in the eaves of the house and some vents the run the entire length of the eaves but thats about it. There are a few cardboard boxes up there that have been there for years and they seem fine, it's freezing up there in the winter and stiffling hot in the summer.

The photo makes the felt look like it's on the wrong way but is on correct, I can actually push the bulging felt back up, I think I might do this and put a couple of wood battons across it to keep it in place.

These insulation boards that are hanging off, is there any point in leaving them there or would you remove them?

I'd be inclined to remove any that are likey to fall of and land on top of those halogens or if they are not too deformed push them back up and fix in place with a battern screwed not nailed as hammering may dislodge tiles.