Filling gaps between slate roof and stone walls

[Ianhaycox]

Hi,

In a barn I'm renovating for gites where the slate roof meets the stone walls (click for a bigger picture) there is a triangular 'gap' between the top of the stones and where the rafters rest on the wall. Also you can see daylight through the gaps on the gable ends.

I wanted to plug the holes to help with sound and heat insulation before plasterboarding. I considered filling the gaps with expanding foam but was concerned it may lift the tiles.

The other option was to mix up a lime mortar and chuck it in the space between the tiles and wall, but I was worried that it may draw moisture and rot the timbers or cause a damp problem. Do I even need to bother ?

Anyone have any experience or suggestions that would be helpful.

Thanks

Ian http://www.brittany-holiday-gites.com/

[Punch]

I would not like to block the gap completely as there should always be an air gap of at least 50mm beneath natural slates. The air should be able to enter from the soffit level and exit from the air vents that are higher up the roof, (if you have had them installed).

On renovation works we  often cut chicken wire in a roll and wedge it into the gap between the rafters at wall top level. This stops birds and pine martins from entering the roof area whilst still allowing air circulation. If there was a wall plate we normally cut noggins to block the majority of the gap leaving a gap for air flow, which is better and more solid.

For sound insulation, if the roof line is properly insulated this should reduce sound anyway. There is nothing wrong with using foam filler but you will need to block off the top section to stop it blocking off air flow. Filler foam is expensive used this way and you would find it would not look very pretty from outside (looking up under the eaves). There is no danger from it lifting the slates and the system you have (stainless steel crochets on battens) is a very secure fixing system and the most widely used for slate roofing.

regards,

Paul