Sealing timber frame to rough stonework ?

[robgraham]

This is the last part of my workshop refurbishment ! The stonework is undressed so the gap between the framework/weatherboarding and the stone is up to an inch and has a howling draft coming through it at the moment.

The solution I see is expanding foam but I'm not sure of the best way to apply it. Options thought of so far -

1 From the outside but will it get all over the stonework? 2 Put a profiled board down the join on the outside and inject from the inside, but then the foam will equally ooze onto the stonework as the profile board won't be that accurate and also the foam will end up in the profiled sections of the weatherboarding. 3 Pack the outside of the joint with newspaper and inject from the inside, but then I wouldn't be able to get rid of the newspaper.

Any other suggestions please. I could have profiled the weatherboarding as I fitted it but rejected that at the time as unnecessary.

Thanks

Rob

[John Rumm]

I take it the weatherboarding sits onto the stonework which steps out wider than the woodwork then?

How about a tilt fillet, with a skirt:

Assuming the existing is like this:

/ / / /

[The Natural Philosopher]

Use duct tape to seal and mask and then inject foam.

It that doesn't stick you have a bit of a problem.

[TMC]

Problem with foam is that it needs painting over to prevent it degrading

Possibly mask off the stone work depending on what tape you can get to stick to it. Inject expanding foam allow to cure paint over then remove masking

or

Profile board on the outside brown frame sealant between board edge and stonework to close any remaining gaps

Repeat on inside for extra draughtproofing

or

Profile board (to prevent mortar falling through) on inside mortar the gap from outside to match stonework mortar

Tony

[Stuart Noble]

Can't quite visualise the overall picture but I think I might go for option 3, perhaps greasing the newspaper to act as a release agent. Foam pipe insulation is quite handy for blocking up odd shaped gaps. I suppose vermiculite is out of the question. Would probably be a good deal cheaper

[Andy Hall]

This does work (I've done it), but it's a good idea to spray the area first with water e.g. from a plant sprayer and to inject the foam a little at a time. Since it expands and cures in the presence of moisture, one can get a better idea of how much expansion will take place sooner. Otherwise, it can go on expanding for several hours if the surfaces and the air are dry - not a problem this week :-) This application isn't to fix anything or to be particularly structural so it's possible to put in foam a little at a time.

With over enthusiasm, it is easily possible to have Peter Parry's Sorceror's Apprentice canoe syndrome and expnading foam is more than able to lift duct tape from a surface.

The other thing is that PU foam does tend to deteriorate in sunlight so a good idea to cover the exterior somehow.

[robgraham]

Sorry John and others - not really a clear description although several good ideas have come forward. The stonework is the wall of the house and the workshop is attached to it, so the problem area is the vertical interface between the rough stonework and the timber framing. I can't remember how the gaps were sealed previously - I suspect not though there was a profiled cover.

Rob

[The Natural Philosopher]

Typically that might be lead folded behind the boards and then pointed into the stonework.

[John Rumm]

Ah, ok, different problem then. I take it you don't want to damage the stone? (otherwise cutting a slot with an angle grinder such that you could dress some lead flashing into the stone could work. Failing that its a case of filling or caulking it with something. Gaffer tape barrier and mortar might be ok. If you ever needed to remove it it should knock off the stone without doing any damage.

[robgraham]

OK guys very many thanks - job done. My concern was the foam getting onto the visible stonework outside the workshop. I masked off the stone at that point with duck tape - stuck nicely; put on a board profiled to the stone and injected from the inside. In the end none of the foam came through (70mm timbers), but the join is sealed and draught tight. I can seal the outside with brown gunge.

One earlier problem I did find a solution to was attaching weatherboarding to concrete blockwork. I realised screwing it on was the attachment method but I was concerned about the wood being in contact with the blocks and that an air gap was desirable. I ended up buying a bag of those plastic shims from Screwfix and stapling them every so often along the inside of the weatherboard plank, and then screwing it on.

Rob

[The Natural Philosopher]

its nice to know when an educated guess actually WORKS :-)

that's also a neat one.