Expansion Joint in Facing brick

[bungle bros]

I've nearly completed a two story extension to my house.

The bottom half of the house is done in facing brick and the top half is roughcasted. There is an expansion joint that runs from the bottom to the top. The roughcasters placed a metal bead in the joint to finish the top half. However, the brickies packed the joint with polystyrene and said I should use silicon to finish.

My questions are

1) Are the brickies correct in packing the joint with polystyrene before filling with silicon, or should I be placing a similar bead as used by the roughcaster's in the expansion joint in the facing brick.

2) The brickies finished around 3 months ago and I haven't got round to sealing the joint with silicon yet. Is this likely to have done any permanent damage to the structure / could cause me problems in the future due to the exposure to the elements?

Thanks.

 

[^woody^]

You dont fit any beads, and what the brickies have done is OK.

Also you should use a polysulphide mastic, and not silicone

 

[bungle bros]

Thanks for that Woody.

Apologies if this is a silly question (I'm not in the building trade), but what's the difference between using silicone and polysulphide mastic? I was going to use the left over silicone that was used on the external window frames (bad idea??).

Also should I be worried about the joint being left exposed for 3 months?

Your advice is much appreciated.

Cheers

 

[^woody^]

You have no worries due to it being open for 3 months.

To be honest, the technical reason why polysulphide is used instead of silicone escapes me

But polysulphide is and should be specified, and has been for as long as I can remember. Its probably to do with elasticity, and longetivity and the thickness of the joint, but exactly why, I don't know.

If you want to use silicone, then go for it. I can't see it causing any major problems as long as you fill it well and smooth it, so that it adheres to the wall properly

 

[bungle bros]

Top man. Thanks again.

 

[masona]

But polysulphide is and should be specified, and has been for as long as I can remember. Its probably to do with elasticity, and longetivity and the thickness of the joint, but exactly why, I don't know.

We have them in our flood wall joints on the coast which can stand up in all weather condition, it's like rubber, heavy duty and it's easy to do a wider joint, it's a nicer finish which is difficult with normal sealant on a wider joint, more details here

 

[bungle bros]

Ah, I think that left over stuff that I have from the window frames is the same brand as the one in your link. Nice one.

Thanks

 

[JamesHughes]

Sorry to butt in, but have exactly the same thing to do on a house I am just about to move in to.

Where is the best (read cheapest) place to get that sealant from? I've checked my usual suspects to no avail.

James

 

[masona]

Have you tried Sealants at Screwfix

 

[^woody^]

Some of the larger mechants should stock it. Not the DIY type ones with a timber yard and some sand, but the proper builders merchants.

 

[JamesHughes]

I did a search on Screwfix for polysulphide, but nothing came up - guess I will have to read the specs carefully unless someone has a direct link.....

James

 

[JamesHughes]

This is silcon based, but seems to do the same thing...

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=76697

Screwfix don't seem to have the polysulphide.

James