Advice sought for small external rendering gap

[dekobock]

Since having a small wall removed as part of a new front drive there's a small gap in the external rendering of my 1930s semi.

Here's a quick picture I snapped on my phone:

question to you experts is simply: what's the best way to deal with this?

I've been advised by a (non-expert) friend to just buy some read-mixed plaster from Homebase and slop it on. But do I not need to insulate it in some way? Or would a small gap like this not need much more than a bit of plaster?

Thanks all!

[dennis]

Plaster isn't water proof so it won't last long outside. IIRC render is a lime/cement mortar which you can also buy in bags.

[A.Lee]

For such a small bit, I'd just use a mortar mix (~6 parts sand to 1 cement) to fill the missing section. You can dapple the surface to get a similar effect to the existing render. I beleive the DIY stores sell a small ready mixed bag of mortar for around £3, or a bag of cement at £4, and a bag of builders sand at £1.50 would do it. Dont make the mix too strong or it'll crack. Alan.

[Cicero]

================================== A bag of sand and a small bag of cement will do the patching. Mix about 4 or 5 parts sand to 1 of cement and water; apply with a trowel.

I would suggest that you get somebody (e.g. a knowledgeable builder) to take a look at the lower part of the render as it appears to be bridging your damp-proof course (if present) and the visible airbrick appears to be at least partly filled with render.

Cic.

[mail]

Dear dekob The point made later on dpc is valid and well observed. but if you have not had a problem then there is an arguement to leave it. To solve the "problem" of the bridged dpc you will need to find it and the bit of absent plaster is the ideal location to look. It also looks to me that the external levels are higher than originally the case with the addtion of paviours so you could start about 2" above them! GLs should be 150mm below the dpc so you may have to remove the paviours close to the house to "comply" (or simply ignore it if there are no symptoms of damp). Additionally, in theory, you should remove all render actually bridging the dpc! to do this you would put on a batten at dpc level and cut upwards at say 45 degrees with an angle grinder so as there is an ovehang of render off which the rain can drip when you have removed a 2" strip of render (or all below the dpc) covering the dpc. Lots and lots of work for possibly no return just to comply with good building practice. Back to render I would do as follows:

1) key the existing surface by raking out mortar joints 20mm and undercut the edges (like a dental filling) 2) spatter coat of 1part Portland cement I part bagged lime 6 parts graded sand for plastering ( you need so little that I would scrounge these or if you have to get a 2 kg bag of sand and cement mix from DIY store and add scrounged lime 3) apply some EXTERNAL (type4) pva (better with SBR) to both the mix and the surface and chuck on a 10mm splatter dash 4) let it set but not dry and add layers to the finish level leaving it distressed to match the existing decorate in a few weeks' time Chris

[Stuart Noble]

Brush the surface with a 4:1 water/pva mix. Get a bag of general purpose mortar from B&Q. Mix it fairly thick. Ignore your friend's advice :-)

Nail a piece of ply or whatever to the right hand wall to give you an edge to render to.

[Stuart Noble]

This is where the ply goes BTW :-)