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Inadequate Subfloor Ventilation - Damp Issues

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Hi all, 

 

We never had a damp and timber survey when buying our house and decided to get a surveyor out after our builder found active woodworm under the floorboards recently. 

 

The surveyor has been out and has advised there are high levels of moisture and not enough subfloor ventilation which is causing the damp issues - He has identified woodworm (weevil) but believes this issue will rectify itself if I can sort of the moisture levels. There is evidence of dry rot and some of the joists have rotted by around 3-5mil. 

 

He has advised that the airbricks (currently terracotta clay air bricks, 1950s property) should be replaced to ensure sufficient airflow, he has recommended to replace these with modern ABS plastic air bricks.

 

I have spoken with a damp company and they have said this will not be enough to increase the subfloor ventilation and he would not recommend plastic airbricks. Please note he has not been to my house to look yet so not sure how he can say this wouldn't be sufficient to increase the airflow? 

 

Can anyone give me some advice, would the plastic airbricks be sufficient to increase the airflow under the subfloor, the surveyor said they do a better job than the clay ones? I do have some of these to the rear of my property and don't seem to have had any issues. 

 

 

Thank you 

 

Edited by Jodie1250

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I expect that modern airbricks would provide more ventilation than the original airbricks, but if you are concerned, you could also have a few extra new airbricks installed.  

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Get more than one opinion/quote.  If they come round and start pressure-selling get someone else.

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Hi Jodie,

 

Did you get damp fixed?  If yes, mind me asking who you had?  We're looking for quotes and looks like we may have had the same surveyor 🙂  

 

Thanks,

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I see may terraced houses with damp floor problems due to tarmac being laid up to the brick wall over the level of the damp course.

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On 11/10/2021 at 14:50, Jodie1250 said:

Please note he has not been to my house to look yet so not sure how he can say this wouldn't be sufficient to increase the airflow? 

Just be careful he doesn't try and sell you an injectable damp proof membrane or something, bit of a sign he's a cowboy.

 

Think about increasing the number of airbricks to increase airflow, but it's also worth looking at your soil stack and any pipework that may be down there.

A leak would obviously cause damp problems, fixing the leak will solve the damp problems.

Edited by geared

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On 15/08/2022 at 21:54, Findlay said:

I see may terraced houses with damp floor problems due to tarmac being laid up to the brick wall over the level of the damp course.

One in Swallownest they actually made a little chute in the tarmac path as the path had got higher than the air brick which just guided rain water into the house.
We have a few where the path slopes towards the hoses sending rain water into the gennels and coal holes to soak into the house, I think one house is getting the path altered by the council to drain away from the house.
Many people allow or cause  damp problems by raising the level of the ground against the house wall, I found an original path in our garden 18" down. 
You can get z shaped vents to get  ventilation under floorboards with higher vent opening outside, helps reduce surface water entry if options are limited.

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