Traditional Materials?

Dec 05, 2017 20 Replies

Where I live I have seen a cycle that goes like this:



Extension built - using timber for things like facias. A few years later the house owner has them replaced with uPVC,



why don't builders use uPVC for new extensions - it it too much trouble for them to source the materials - or is it the home owners fault for not specifying uPVC?


Buy wood. Prime it, undercoat, gloss. That's cheaper than PVC?

When I had the dormer containing our en-suite bathroom replaced at our last house, wood was still cheaper.

And yet in the past wood was able to last a very long time. What has changed? Wood treatments and weathering etc? Brian

we've had to replace most of our timber window frames - they were only around 90 years old. Mind you, some of the Magnet jointery ones in the extension needed replacing after just 42 years.

Slow grown wood was denser and lasted longer.

Then there was a phase where they used untreated fast grown wood and that rots if it smells water.

Now building regs require wood to be treated in most cases so it doesn't rot as easily.

Use plastic you know it makes sense.

People can't be arsed to paint them every few years, I know I can't.

Prime it? Undercoat it? Ha Ha Ha Ha...

You were perhaps assuming DIY quality...

Yes, when I replaced my own facias, I bought the timber, left it for several months so I could discard the bits that went banana shaped, then cut and temporarily fit to get sizing right, took down, rot proofed all sides, aluminium primer all sides, undercoat all sides, top coats (front only, to allow rear to breath), and then screw back up.

Ten years later I had scoffolding up for some other reason, so I took the opportunity to take them down, inspect, wipe clean (was all it needed), and refit.

It's now another 8 years on, and they still look like new.

Maybe I should have fitted uPVC. Didn't have any experience of using it, and there was no profile that matched at the time, and it needed to be black which was a more limited option.

I guess many just don't make a conscious decision - they leave it to the builders and then when it starts to look a bit scruffy they get it replaced.

You might also ask why the builders didn't use better quality timber in the first place.

So the answer is they wanted the maximum profit over quality.

You are lucky. I had one which was rotten in about 15 years. Despite being kept well decorated.

Wood treatments. Arsenic and copper now banned.

The sun normally plays havoc with black-painted timber.

You can paint Upvc black, I've seen it done near me. Looks ok (from ground level).

The problem is the ends of the timber which are never sealed in any way. Pre-primed timber is cut on site without bothering to treat the cut ends. These are not visible to the eye being hidden by the rest of the structure, but rain soon gets in, especially if the cut end is the bottom of a vertical piece of timber.

Classic 1970's bodge was a porch made of a standard 2'9" external softwood doorframe joined at 90 degrees to a full depth feature window 4' 0.25" wide using a bit of 3x3 softwood the same depth, to act as the external corner joining piece. Flat roof on top.

The bottom of the 3x3 corner piece usually left as bare wood sitting on the dpc. Average life before the owner gives up and replaces the whole lot with upvc/dg - about 7 years.

Softwood PAR is pretty standard these days. It's the lack of attention to sealing all bare wood, *including* cuts that are not visible that is the problem.

This needs more time and time is money.

John Carr gives a 30 years anti-rot guarantee on some of their timber doors and windows now, so they must have improved their production processes. However it only needs cack-handed installation of damage the factory finish and ruin that potential 30 year life.

I've heard it's because we build out of green wood, so the first coat doesn't stick properly, and it never dries out.

Andy

Timber used before WW1 was very different stuff from that used after it.

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