Damp Under & to Side of Sash Window

[netpet]

After living in this house for 14 years, three patches of damp have appeared under and to the side of an external sash window.

The strange thing is that the other side of the wall abuts to an extension roof and is not exposed to the elements. There's a groove under the cill, the seals are all in good order, and the window itself is in good condition.

I've attached quite a few photos, both close up and from the outside.

With thanks for any help you can offer.

Annette

Under the Cill

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• 8 Aug 2012
• 1

Under the Cill - Close Up

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• 8 Aug 2012
• 1

Windown Cill from Top

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• 8 Aug 2012
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Damp Patches Underneath

• netpet
• 8 Aug 2012
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Side Damp Patch

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• 8 Aug 2012
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Back of House

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• 8 Aug 2012
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External View of Window

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• 8 Aug 2012
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Untitled

• netpet
• 8 Aug 2012
• 1

Damp Patches - Close Up

• netpet
• 8 Aug 2012
• 1

 

[ZUNDAP]

Have you checked the mastic seal where the window touches the wall?

Another possibility is that you have a leeky roof and the water is running
down the cavity and then it may arrive at the point at the window, its a long shot, but i have come across this problem a couple of times.

Another option is to use a damp metre and trace back to the wettest point.

Good luck.

 

[HERTS P&D]

There is an overflow just under the gutter, my bet is the float valve in the cold water tank is faulty and overflowing over the night time but not when anything is used. Thus causing the water to drop down and hit the wall causing damp penetration through the wall.

I'll get my coat.

Andy

 

[netpet]

Thank you for your suggestions.

Hertsdrainage2010, you're a complete star. You're right, I remember one of my housemates saying she'd seen water coming from the overflow one night, and I have had problems with limescale clogging up the float value in the past. I'm going to get it fixed and am sure that the damp will disappear.

Your advice has saved me £5,000. A roofer was trying to tell me the back of the house needed repointing and resealing, and all the paint on the bricks needed stripping. Thank you, thank you, thank you.

 

[HERTS P&D]

Many Thanks for letting me know, I have included a picture of what needs to be changed -

http://www.screwfix.com/p/pegler-prestex-float-valve-part-2/27627

You have these fitted to the cold water storage tank and the expansion tank. The cold water storage tank is the very large tank and the expansion tank is the small one, for the heating. (if needed- depending on the heating system you have)

I would advise to change both at the same time.

You could also have the overflow pipe work extended so that in the future the water will fall onto the extension roof and not against the wall. All your plumber will have to do is cut the pipe work in the loft and push it through the facia board by 150mm and put a new piece of pipe work in the loft with two straight connectors.

Andy