Musty damp smell - airbricks blocked?

[mater]

i might be wrong but are new houses pressure tested now? i built some last year for housing association and these were pressure tested and passed with no problems

 

[peteuk]

Thank you all for your interest.
Like the humour - LOL
To answer a few points:
- I did ask the cavity wall installer to come back and review the job. (I hadn't discovered this wonderful site then).
Unfortunately the company sent the same guy who'd done the installation so he was hardly impartial
He said he always filled the airbricks with mastic to prevent the insulation getting wet in driving rain. When I said the airbrick must have been put in because it was needed he didn't have an answer. No mention of sleeving was made. (I can't recall if I knew about it then)
When I showed him an airbrick where there was no insulation behind the mastic he just said he'd done it right.
(We have a wooden floor under an extension which I pointed out to him. He said he didn't fill the walls there because of the need for airflow).
I didn't know who to ask about getting the job checked to make sure there were no voids etc so I let it go.......
- Don't think the airbricks are sleeved because we had a similar damp smell in 1 of the kitchen cupboards. The solution we did there was to fit an additional airbrick and make a hole in the internal wall of the house behind the cupboard to provide ventilation. I wasn't there when it was done but I don't think there was sign of any insulation or sleeving on any nearby airbricks.
- The leak was from a frozen pipe, I think in the loft (heating was left off). Not sure if mains or heating. Anyway no-one lived here at the time so I think a quite major flood but not for months. Walls were replastered at least.
- Re: Woody's and Perryone's comments:
"As you don't have a timber floor" - wouldn't a block and beam floor have wood construction and therefore be suspect? Hence my idea to remove an airbrick and have a look.
"you will need to strip off all wall coverings, wipe the walls down and then seal them before redecorating. Same for the floor, and ceiling." Ouch! We've just decorated! I'm a bit in denial about this because of it - but maybe it's where I'll end up?
"add some ventilation" - window now permanently open in 1st position even though it's a ground floor bungalow
"You should also block up the vents" - conflicting advice on this site about this. You are echoing what the installer said but seeing as how I can't see the insulation I wonder whether or not this is the cause.
I feel that some points are valid on both sides. I just wish I had delayed the cavity wall insulation until we'd lived here a bit so that I could have compared the difference. Instead I feel I may have caused a problem and don't know how to investigate the root cause.

A few other points / questions:
I will recheck the loft insulation to see if that could be too close to the eaves.
I had facia and soffit boards fitted. Small round vents are fitted every couple of metres. Could lack of ventilation here be a factor?
Is my idea to examine the cavity around 1 of the lower airbricks worthwhile? (I'm not practical so have to ask someone to do the job or help. If I'm wasting my time I'd rather not spend the money)

Sorry for the long post & thank you for your patience


Pete

 

[stuart45]

The idea that the remedial process blown cavity wall insulation would ever work amazes me.
You are aware that no new building would ever be so constructed

New houses are sometimes built and retro filled with blown insulation. It is thought to be cost effective compared to the cost of the bricklayers fitting it.

 

[PerryOne]

It is perfectly possible that all your damp problems are down to that leaking pipe and that over the next months or couple of years the damp will go - never the less read on.


You can understand the builders remark about driving rain, entering the building, making the cavity wall insulation wet and the wet being transferred to the inner wall, making it wet in turn and creating an easy escape for your heat.

There will only be a need for a sleeve where the air brick is in place to ventilate the room (and that will be obvious by it being matched by an inner air brick facing the outer air brick) otherwise the sleeve is unnecessary as the air vent is there to vent the cavity wall.

Having no insulation behind the air brick in the cavity does not give one much hope for the rest of the walls integrity? (the first cold spot)

I am not sure of the next paragraph. Why did he not insulate the walls in the extension? What connection has the wall with the wooden floor?

As a matter of fact, the idea of lots of air bricks under floors to improve the ventilation and therefore drying of joists and boards has gone out the window.

The situation where air is sucked under a floor by the passing wind, or is sucked in by the air inside the home rising and going out the windows, doors and other gaps in the home has been discredited.

There has been a realisation that the arrival of warm wet air under a home,that promptly condenses on the cold joists and leads to mould and wood rot is not the way to go.

The modern idea is that warm wet air must be kept outside the home and the move to Passive House standards in 2016 will resolve this.

The way to check (and you cannot beat doing things yourself) is to buy an infrared temperature gauge and a decent damp meter.

Sweep the walls with the temperature gun, you will be surprised how the temperatures will vary on different walls. Identify where the cold spots are (do this when you have had the heating on for some time and the temperature has settled)
Having identified the cold spots check them out with the damp meter and compare with elsewhere.

Another way, more expensive, is to have some thermal photos taken from the inside and outside (preferably on a cold day) these will give you a clear perfect picture of where the insulation is missing and where the damp patches are. You can then ask the installers for their comments.

The leaking pipe, if on the mains side would have delivered an enormous amount of water into the home.

Probably all your fears about damp are groundless as a large amount of water takes a long time to completely dry out. Possibly as long as three years.

Years ago, it was normal for a new built home to be left empty for a year to dry out, before a family took up residence.

Adding air bricks will lessen the smell, with outside air diluting the air in the kitchen, but, every time you add an air brick not only do you
add more dry air to the room (the air outside is nearly always dryer than indoors [in this country]) you also bring in cold air and loose your warm air, adding to the cost of heating your home.

The indications are that you do have a wooden suspended floor (by virtue of the air bricks) but do take a look (smash one of the air bricks below the floor and take a look from the outside)
block it up afterwards to stop small creatures making a home indoors.

Add some ventilation, see above re 2016 and the move to controlled mechanical ventilation.

However, we all breath out totally saturated breath and tend to sweat, this water vapour adds about 1.5 litres of water vapour to our home per person every 24 hours. Small children an animals being more active add more, old people add less. This water vapour plus that from washing needs to be vented to the outside and bathroom and kitchen extractor fans solve part of the problem and part open windows for a short time every day will control the rest.

Unfortunately, open windows can be forgotten and the amount of ventilation will greatly vary greatly depending on the wind.

Never the less a permanently open air brick/vent will cost you a great deal of money and controlled venting by opening windows is better.

Why did you have the work done on the loft?
What did you hope to achieve?

I believe that information is important, it may not be what you want to read but, at the end of the day you are aware of further possibilities and can research and make your mind up.

 

[^woody^]

From the OP, there is no indication at all that there is a damp problem.

It's no good recommending an amateur use some instruments to check for damp, when they will have no clue at all what they are looking for, and what the readings actually mean. A damp meter reading "damp" does not mean that there is dampness.

And a thermograph is going to be no use at all for the OP's problem

A wall is going to have cooler areas. Any cooler part of a wall is going to show higher moisture levels than a warmer part. Exactly what is this going to determine? And what is the OP supposed to do about naturally occurring cool spots?

If there was a damp problem then it would be visible. There is no timber floor.

 

[peteuk]

Thanks for the replies, and what a lot to take in.

Thoughts and answers:

- When we bought the bungalow it was empty so I asked to accompany the surveyor we employed. As part of his inspection he used a meter in some of the walls to check for damp. At the time he said it was dry.
Having read sceptical comments on this site about the reliability of such readings I am not sure I am well placed to do this again for myself.
Plus the fact we have have no visible signs of damp suggests I'll ponder this one. Likewise the thermal imaging.
Woody's comments suggest I may not get results that I trust anyway.

- When we moved in there was about an inch of insulation only. So I added more. Could be I got it too close to the eaves. (It's counter intuitive not to, even though I tried to resist sealing it tight).
This and the cavity wall insulation were my idea of following popular advice in the media etc.....

- The soffits and facias were decorative more than anything else - (OH request - in hindsight I should have had it done differently and old wood removed etc....)

- Think I'll open up an airbrick to see what we can see. My concern here is to identify if I need underfloor ventilation for a block and beam construction in the original part of the house. If I do then I thought this could be contributing to the mustiness if the airbrick is blocked.
If anyone think this is a really stupid idea please tell me and why. There doesn't seem to be any logical path to getting the exact answer

Thanks again - will let you know how I get on...may be a little while to get sorted. In the meantime other thoughts gratefully received.

 

[Nige F]

It is perfectly possible that all your damp problems are down to that leaking pipe and that over the next months or couple of years the damp will go - never the less read on.



I As a matter of fact, the idea of lots of air bricks under floors to improve the ventilation and therefore drying of joists and boards has gone out the window.

, or is sucked in by the air inside the home rising and going out the windows, has been discredited.

been a realisation that the arrival of warm wet air under a home,that promptly condenses on the cold joists and leads to mould and wood rot is not the way to go.

The modern idea is that warm wet air must be kept outside the home





Adding air bricks will lessen the smell, with outside air diluting the air in the kitchen, but, every time you add an air brick not only do you

add more dry air to the room (the air outside is nearly always dryer than indoors [in this country])

Add some ventilation, see above re 2016 and the move to controlled mechanical ventilation.


Unfortunately, open windows can be forgotten and the amount of ventilation ..... and controlled venting by opening windows is better.

research and make your mind up.

I`ve made my mind up already...Rising damp does exist

 

[PerryOne]

peteuk
I do agree with your comment - rising damp does exist.
When I bought this bungalow not only did I have rising damp, I had water rising up through the tiles on the utility room floor and flowing out under our back door. Wonderful people builders.