Roof repair, timber treatment and moss cleaning

Hi all, we have just received a quote for some roof repairs from a French company Maison Sur.

The gable end of the house joins onto the roof of our barn which is at right angles to the house. Ever since we bought the house and according to friends who knew the previous owners there has been a leak in times of heavy rain.

I have tried with a friend three times to cure this but our patches have never completely worked. We have reached the stage where we were seriously considering removing the roof and remaking the channel between the end of the house and the barn roof.

The roof 18m x 7 each side comprises corrugated fibre concrete panels with canal tiles placed on top. The canal tiles have been fixed together with mastic although a few have started slipping.

We have been quoted €5500 to fix the roof and €6400 to treat all the roof timbers with pressure injected Xilix 500 pro. Finally the roof has quite a bit of moss and we are being quoted €5500 to clean the moss and treat the roof (spraying the canal tiles) with a hydrofuge.

I am inclined to do the repaire but not do do the roof cleaning and treatment but am unsure about the Capricorn treatment.

Any advice welcome and does anyone have experience with Maison sur.

Regards Nick

Is there any sign of damage in your roof beams?

And you could probably do moss yourself for €100 with a pressure sprayer and bleach,

I’d do any treatments myself but better ask our resident pest controller @Rob_le_Pest what he thinks

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I know French and UK prices are not directly comparable but that sounds a lot for moss removal - we have a bungalow here in Surrey with quite a big roof area, and de-mossing was under £2K last time IIRC.

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Bonsoir :blush:

3 things here, Firstly as @JaneJones says, the moss on the roof can be done relatively cheaply. 5K€ does seem awfully expensive.

Roof repairs I’m not a roofer and I have no idea of repair costs but would recommend getting several quotes.

With regard to Xilix 500, it’s a very good product, it’s a gloopy insecticide for treating wood. I personally have real issues with the application. Firstly the wood needs to be completely dry, so the roof needs repairing first.

I don’t like injecting; In my opinion it has no extra benefit over surface spraying, the plastic plugs are an eyesore and you’ll regret it for the rest of the duration you have your house. The cost is crazy too, from 100 to 150€HT per linear metre. Surface spraying with a less gloopy Xilix 3000P you could probably take a zero off the quote.

Personally I wouldn’t charge 6.4€K for a surface treatment, and I wouldn’t pay that either.

I reread your comment. Yes it would work, but it’s somewhat illegal. Most ‘door-knockers’ who offer the treatment use neat chlorine, equally aggressive and not PC. :joy:.

Other legal products are available, but not the 5€K the OP was quoted!

From previous work where chlorine bleach was considered not PC, I did extensive looking into the alternatives being used. The alternatives were much longer lasting in their effects on water courses and by definintion lakes etc. At least chlorine bleach breaks down quickly into almost harmless compounds. Not to mention thevalternatives being 4-5 times the price.


We are having our roof treated and spraying with a pressure washer will damage the tiles.
Here the moss will be scraped off, removed and then the tiles treated, but certainly not with a pressure washer.

Agreed. We have VERY elderly curved roof tiles. Pressure washing would be fatal.

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And with water delivered at that speed and pressure a big chance of a serious leak/flood.
I once cut through the render on a block of flats with my pressure washer whilst removing grafitti.


Thanks Rob, I was happy with the roof quote, as it involves making new gully’s in zinc, but unsure about the wood treatment.

The injectectors sticking out as they will all be in the attic space but if as you say it is very expensive we might back out of that part. We were told we have 14 days to change our minds.

Thanks Nick

It is not recommended to use high pressure on tiles. But low pressure will help cleaning the tiles well, after having sprayed the appropriate product.

Scraping can be done before treating with hydrofuge incolore (or coloré) if dead moss or dust remains on the roof.


A 50 bar washer should be OK but not the HP 200+ washers.

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Yes, our guy certainly seems to know what he is doing.
He worked with his father before he retired.

But did his father know what he was doing :wink: