Insulating where joists meet the wall

[Richard Knight]

We have a completely uninsulated roof which is a project I'm about to tackle. Upon closer inspection it seems that where the roof joists meet the wall there is in some instance a fair amount of gap to the outside world. The largest I've found so far is say 5cm by 5cm or so.

What substance should I use to fill this? Mortar or foam? I'm conscious that the latter may be strong enough to push the tiles up if used too enthusiastically but then the holes are quite big for just mortar....?

Appreciate your views.
Richard

 

[masona]

Any photo?

 

[Richard Knight]

You can find a couple of pictures here:

http://www.marsbrook.com/roof.htm

Prior to actually putting up a new ceiling in the room in question and insulating I was thinking of doing the following:

1. Some of the tiles leak when it rains hard and / or with strong wind. This is where the gaps between tiles are too large, the mortar has disintegrated and in some cases is exacerbated by the slope of the tile being next to nothing (there's not much pitch on a roof in this area). For this I am planning to fill offending gaps between tiles with fresh mortar.
2. Fill in the larger holes near at the top of wall / base of joists

The roof will never be 'holeless' - there's no lining, it's just tiles on rafters and then ...the house. In this instance a 3rd floor which is currently just loft space.

Thanks,
Richard[/url]

 

[masona]

Ahh right, a spanish type of roof, I was wondering can you pack the tiles up a bit by using the timber on the side of the joists and use roofing sealant as the tiles appears to drop hence giving you a bad fall.
Is the roof like this one?

 

[Richard Knight]

Yes - that’s exactly the sort of roof we have.

If I understand correctly you’re suggesting ‘propping up’ the tiles a bit where they drop (& hence we get leaks) by supporting them with something attached between the joists…e.g. another bit of wood. Then to apply roofing sealant along any remaining gap between the tiles thereby making a weatherproof seal? Is that right?

If so, then yes, sounds like a good idea. I could just do the above where we suffer worst from leaks and of course, by doing it this way rather than just filling the gap with mortar I’d actually stop the problem happening in that area again as the tiles would have additional support.

Regards,
Richard

 

[masona]

Yes that's right, seems like the tiles has drop a bit and need putting back up.

 

[Richard Knight]

Perfect - thanks for your help.

One last question - what is roofing sealant...I mean, I understand it's a sealant. A better question is how is it applied and hence what am I looking for? Is it a canister like silicon sealant and also applied using a 'gun'?

Thanks,
Richard