How should I protect newly exposed vertical plaster from the elements?

Kernel_Sanders

I've been given a decent 2nd hand PVCu d/g portrait window to replace my rotting wooden one, but it's about 80mm narrower. It's a double brick wall (no cavity), but the inner half of the reveal is so thickly plastered (it looks like two coats) that the new window will fit with just an 8mm gap (each side) between frame and plaster. That leaves two vertical strips of about 32mm of exposed plaster facing the street, with maybe a 40mm horizontal srtip across the top. What's the best way to fill these gaps and protect the plaster from the sou'westerlies that it faces?

Furts

Gun grade expanding foam to fill the gap. This can be controlled to do a careful filling. Then use pvc white flat trims over the top, sealed to the window and against the wall. Use white silicone for the sealing.

Inside the room will also need sealing. Again pvc trims are usual, but I am not always a fan of these in this location. Regardless, this is the quick, cheap solution. Make sure there is a good bead of sealant for draught and moisture sealing.

Kernel_Sanders

gun grade? trims? This sounds a little specialised for me!

Kernel_Sanders

Furts wrote: »

Gun grade expanding foam to fill the gap. This can be controlled to do a careful filling. Then use pvc white flat trims over the top, sealed to the window and against the wall. Use white silicone for the sealing.

That's a huge width of plastic, at least 40mm, to add to the frame width. I've taken a pic as I was wondering if instead some sort of render could be applied to that 32mm strip of plaster (although if you zoom in you can see that it seems to be a thin layer of plaster on top of something else). It's recessed by a few mm so that a render needn't protrude outwards any further than the frame.

Ruski

Use frame extenders, that's what they're designed to do.


HTH


Russ

Furts

Kernel_Sanders wrote: »

That's a huge width of plastic, at least 40mm, to add to the frame width. I've taken a pic as I was wondering if instead some sort of render could be applied to that 32mm strip of plaster (although if you zoom in you can see that it seems to be a thin layer of plaster on top of something else). It's recessed by a few mm so that a render needn't protrude outwards any further than the frame.

My thoughts are a little bit of render will not stick,nor be durable in this location. Plus to apply the render the surface finish of the plastic profile will be scratched and damaged.

I take on board Ruski's comments, add on pieces would work if this is the old conservatory before it was re-erected and the render was hacked back first.

Assuming this is the new, finished, conservatory then I would be putting trim pieces on here. This would be a quick, simple, solution and be acceptable to most people.

Kernel_Sanders

Furts wrote: »

add on pieces would work if this is the old conservatory before it was re-erected and the render was hacked back first.
Assuming this is the new, finished, conservatory...

I'm stumped as to why you assume it's a conservatory! The only thing I can see that might have misled you is the street scene you can see in the window; the pic was taken from the outside and thus that is a reflection. It's a bog-standard Edwardian terrace, and the pic is of the replacement window. The rotten wooden window it replaced stretched the full width between the bricks and also had badly cracked glass, which someone reported to Environmental Health. They told me to replace or board up, but unfortunately they reinspected before I got round to finishing it, and have now told me that they have passed the case onto BC. I'm therefore reluctant to spend too much* finishing it in case they order me to take it out. The unit is laser-printed Jan 2006, although it's next to the front door so no 'means of escape' window is needed.

* This means I don't want to shell out £18 for a gun, especially after reading this review (Screwfix): Unless you can take it apart for cleaning, any foam gun will sooner or later clog up. It is a consumable which cannot be expected to last more than 3 to 6 months. This gun lasts longer than most if the instructions are followed. It is well made and dispenses with accuracy.

tony6403

Ruski is right that frame extenders or "knock on" is the way to go - e.g
http://www.windowforce.co.uk/Knock-Ons---Extras-ct739.html
An alternative would be to attach lengths of treated timber symmetrically around the aperture (plugged and screwed into the bed joints) and then screw the window frame to that.
Bullnosed UPVC trim could be used to cover the facing edge of the timber and slightly overlap the window frame.