Replace wooden window frame with concrete?

George_Bray

What would you do here, please? The patio window is part of an extension. Perhaps the builders left an inadequate gap (height) between the paving slabs and the lower part of the wooden frame, 20 years ago. It may have been too exposed to rain water over all that time. Anyway, the lower strip of wood has rotted away and needs replacing.

I'm minded to use concrete rather than wood, to stop it rotting again. Is there any reason why concrete may not be such a good idea? I can use a waterproof membrane at the interface between the concrete and aluminium.

I can even paint the concrete brown to help it blend in with the rest of the frame (uprights and top bar) which will remain wood.



Regards
George

flang

I dont see how your going to replace a wooden frame with concrete.
Surley the patio doors screws into that wooden frame? so if you need to replace the bottom of the frame surley the whole door would have to come off?
Personally i would just replace it with treated wood and make sure a damp proof course membrane is put underneath it should last for at least 10 years!

George_Bray

flang wrote:

I dont see how your going to replace a wooden frame with concrete. Surley the patio doors screws into that wooden frame? so if you need to replace the bottom of the frame surley the whole door would have to come off?

Thank you for your suggestion. The wood is so rotten that it just pulls away leaving a void with the frame fixing screws hanging down into thin air. So if I pack the underside of the frame with concrete, the concrete will grip and surround the screws better than any rawlplug, presumably. The upward force of the concrete will also mesh perfectly with the contours of the frame. That was my thinking anyway. But are there any other disadvantages with concrete I'm wondering? The advantage (hope) is that it should last nearer 50 years than 10 years.

Regards
George

flang

George the problem you might have is when water drips down the window insted of it dripping onto the wooden ledge then onto the floor will drip on to the concrete and soak away right next to the brickwork which could cause dampness.

George_Bray

Flang

What I've decided to do is form a sandwich of wood on the inside and the outside, with concrete hidden in the middle, directly under the frame. This will enable me to swap the wood elements quite easily and at moderate cost in future, if the wood ever rots again, despite using treated timber and various protective coatings. I am also using waterproof membranes and/or external frame sealant between (a) concrete and aluminium, to prevent any chemical degradation of the aluminium door frame, and (b) between wood and concrete - just like for any wooden door frame. The reason for this somewhat unusual approach is twofold: firstly to save on the presumed substantial cost of a new hardwood threshold and secondly, the near impossibility of installing a wooden threshold without removing the entire patio door frame - a task I want to avoid. My expectations are (1) that, from now on, the interior strip of wood will never get damper than from internal condensation. There's no way that rainwater will be able to reach the internal strip of wood. (2) The concrete should stay dry as well, since it is surrounded by plastic sheet and sealant. The external wood strip will be exposed to rain water but will be protected and can always be renewed easily and cheaply.

The costs of the entire job are minimal - a few £10s rather than presumed £100s or £1000s if I called in a builder to do the job 'properly' i.e. remove the entire frame and purchase a huge new hardwood beam. I'm sure this would not last as long as my solution.

Concrete is so cheap it's almost free. Timber costs have been minimised by setting the concrete to accommodate off-the-shelf strips of wood, like 19mm x 38mm for the interior wood.

An additional WARNING to anyone with this basic style of patio doors/windows – as Flang correctly pointed out, there are screws which go down from the bottom of the alumimium frame into the wood (now concrete underneath). The so-called professional builder who presumably installed the doors 20 years ago made a mistake, in my opinion, by using ordinary steel screws, rather than stainless steel. The low quality screws have partially rusted away. He also failed to seal the tops of the screws. So for years, I now realise, rain water has been passing down through the screw holes into the wood, causing serious wood decay. That’s what you get when you pay £100s or £1000s for a professional. TIP - change your screws for stainless, and be sure to seal the top with some silicon or something.

Regards
George