Musty damp smell - airbricks blocked?

[peteuk]

Hi,

I hope someone can help me with this?
We have a damp musty smell in a bedroom which as a child I would have described as the smell of an 'old person's house'
We bought our bungalow in 2005 and I had cavity wall insulation installed. There are airbricks ar the top and bottom of the external walls of the bedroom (on the North side).
The installer sealed these but I have removed the sealant on the basis that the cavity needed some ventilation or the air bricks wouldn't be there.
There was no sign of insulation behind the airbricks.
When poking a 'stick' through the airbrick there is no opposite opening in the internal wall (no visible vents inside the house).
My floor looks like concrete but I guess it could be block and beam which could therefore have some wood construction. How can I tell?
My thoughts are that we may have blocked a vent which goes under the floor and hence causing damp which may be causing the smell in the bedroom.
Is this likely?
My idea is to ask a builder to remove an airbrick and see if I can find evidence of a problem.
Does anyone have any thoughts on this?
Eg. Will we be able to see anything that will help diagnose the problem?
Is there a more practical route?

Thank you for any advice

 

[JohnD]

How old is your house?

Are there airbricks to ventilate the underfloor void?

Do you have flowerbeds, paths etc above the level of the damp course in the walls?

have you checked for leaky gutters, downpipes, radiators?

does your lifestyle include any of the common causes of damp? draping wet washing about the house, keeping windows closed, failing to use extractor in bathroom etc?

more ideas in //www.diynot.com/wiki/building:condensation_in_houses

 

[cmother1]

When you say "old person's house" is this a polite way of saying "wee"? A badly done cavity wall insulation job can leave a smell of formaldehyde in a property more or less indefinitely. It smells remarkably p*ssy. I'm sure this was the the cause of weird smells in my in-laws old place.

 

[Nige F]

indefinitely. It smells remarkably LIKE p*ssy. .

 

[cmother1]

Oi - where did that "LIKE" come from. You rude boy!

 

[peteuk]

Thank you all for all your replies.
In answer to the questions:
How old is your house? Late 1950s, early sixties I think
Are there airbricks to ventilate the underfloor void? The airbricks are above the damp proof course on the external wall. The internal wall in the bedroom does not have airbricks in. My question and proposal was because I wondered if there could be a underfloor void or airbrick in the internal wall that is not in line.
Do you have flowerbeds, paths etc above the level of the damp course in the walls? No, When we moved in there was a concrete slab 3" under the DPC. We now have block paving 6" under.
have you checked for leaky gutters, downpipes, radiators? No signs of leakage
does your lifestyle include any of the common causes of damp? draping wet washing about the house, keeping windows closed, failing to use extractor in bathroom etc? Window in the worst room often closed, little window now opened in "trickle position". We don't put washing on radiators. I don't think the previous fan in the bathroom was up to the job so have just installed a more powerful one - you can now feel the draught!
When you say "old person's house" is this a polite way of saying "wee"? No, it's never smelt of wee.

A bit more background:
- Before we bought the house it had been empty for 18months and had suffered a leak - repaired before we moved in.
- We had a leak from the roof in another area of the house but we believe that's been fixed for many months now.
- In addition to the cavity wall insulation we put loft insulation down.
- Soon after we moved in, the bed we had in the worst bedroom started to smell foisty. We replaced it and no problems with the new bed - we put it down to moisture from plasterwork etc as we renovated.
We have no signs of mould anywhere that we can see.

All ideas appreciated.
Thanks

 

[joe-90]

- We had a leak from the roof

Exhibitionist huh?

 

[churchilldog]

The installer sealed these but I have removed the sealant on the basis that the cavity needed some ventilation or the air bricks wouldn't be there.
There was no sign of insulation behind the airbricks.

Surely the cavity can't ventilate as it is full of whatever the insulation is? Question how well it has been done though if you can't see insulation behind the airbricks- are you sure they weren't sleeved through the cavity- although if this had been done they shouldn't have been sealed!

 

[cmother1]

This leak that occurred when the place was empty, but fixed before you moved in... Any idea where and how serious. If it was a water main, and soaking into the sub-floor for months possibly, it could take years to dry out. This happened in my parents place and it wasn't even their water main - it was next door's. Luckily the house was rented so the landlord had to pay for the section of floor that caved in.

 

[^woody^]

This musty smell is going to have one of two sources

it is either some damp/rot under a timber floor

or it is just a stale old unventilated room

As you don't have a timber floor, and there are no other signs of damp or mould, then that discounts the first option

For the second, 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.

And add some ventilation.

If this is an old smell, then its in the structure, and wont go away by ventilation alone

You should also block up the vents. If the cavity wall installer sealed these, then he did so for a very good reason - to stop damp air getting to the [fibre] insulation to stop it being wrecked.

 

[PerryOne]

Cavity wall insulation is very often the cause of damp problems and is rarely the solution to cold walls and rooms as promoted.

Cavity wall insulation was someones idea, to add insulation to existing properties and to make a lot of money in so doing.

Cavity wall insulation should only be installed when you are certain that your outside walls are waterproof and that they will never ever leak in the future.

Cavity walls were invented because wind blown rain runs through solid walls and results in wet plaster,wallpaper, wood, carpets, and is not nice.

The cavity wall idea was that the rain would blow/run through the outer wall then run down the inside of the outer wall and out at the bottom. Leaving the inner skin dry.

The problem this created is that, the inside wall provides very little insulation, and is like living in a tent.

Builders ever thoughtful provided air vents in the outer skin to ensure the wind blows through the cavity, the walls act like a refrigerator and keep the people indoors cold and miserable.

And these days trying to cope with massive heating bills.

So there you have it, cavity walls mean cold homes, but filling the cavity with blown insulation causes its own problems.

The first is, when rain comes through the outer wall it makes the insulation wet, this in turn makes the inner wall wet, and this provides an express route outwards for all your expensive heat.
As warm always moves to cold and the heat in your home heads outwards. Once air has a space wider than 16mm it starts to rotate. a As it rotates, it transfers the heat from the inner wall across the cavity to the outside wall.

The next is that cavity wall insulation is only as good as the person who installs it makes it. It is not unusual to find large holes in the insulation frequently in corners of walls where the insulation has not filled the cavity and round windows and doors.

The problem with these holes is, that the areas of wall that are not insulated are then a lot colder than the rest of the walls – these areas have the insulation equivalent of an old thin double glazed window.

You have seen the condensation that forms on windows overnight when the temperature drops, sometimes windows running with condensation, this happens with your walls as well, except that the water vapour soaks into the walls and makes a damp patch. These damp patches both inside the cavity and in the room then provide a home for mould to grow and as mould grows it fruits and gives off spores that move about the home and smell.

You should not be too concerned about blocked air bricks as from 2016 all new homes built in the UK will have to be of Passive House standard – this means air tight, with forced ventilation.

 

[^woody^]

Cavity wall insulation should only be installed when you are certain that your outside walls are waterproof and that they will never ever leak in the future.

condensation ...forms on windows overnight when the temperature drops, .... this happens with your walls as well, except that the water vapour soaks into the walls and makes a damp patch.

For the first statement, that makes every single building material unsuitable, as they all either get wet or can't be guaranteed to stay dry. So cavity wall insualtion is unsuitable in all walls?

For the second, that is fundamentally wrong. It is the relationship between the temperature and dew point of the air and of the material that causes moisture to condense. There is no automatic condensing of air into walls

Plaster is hygroscopic, but that is completely different to your comparision with condensation on glass.

 

[PerryOne]

For the last two thousand years people have built homes/houses from the materials at hand.
Until recently homes/houses were not designed as waterproof and the natural way of things was to produce homes/buildings that shed water got wet and used the convection and movement of air to dry them out.
Modern homes are still made of porous materials and they are full of holes, they also soak up water.
Modern factories and office blocks tend to be made of waterproof materials like glass, steel and plastic.
Until our Government understands that today's building standards are totally wrong then people will continue to live in damp cold homes.
There are millions of homes that are damp and cold.
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.
I really do look forward to 2016 when the new Passive House standards come into force - I will be pleasantly surprised if any builder can consistently produce class six buildings (if ever)

 

[noseall]

For the last two thousand years people have built homes/houses from the materials at hand.

...and probably for the next two thousand, Einstein.

Modern homes are still made of porous materials and they are full of holes, they also soak up water.

....and they readily evaporate most of that moisture also.

 

[Nige F]

It`s not the house/it`s construction. It`s the way people live in them I`ve been in enough places with that "sticky fuggy " atmosphere to last me a lifetime. OPEN the FREAKIN` WINDOWS