Condensation inside my house due to cavity wall insulation??

[Virgil]

Weve lived in this house for a few years and never had any problem with condensation. We had cavity wall insulation put in last autumn and the house was much warmer over the winter. But now the weather has warmed up the house is freezing and today we've come home to wet floors which we think is condensation. Could this be because of the cavity wall insulation?

Anyone?

no.

In case of condensation, add ventilation. If that doesn't cure it, add more ventilation.

In the case of a wet concrete floor, find and fix the leak in the pipe (or add a DPM if there is none)

Thanks pigletjohn. It's strange the house is absolutely freezing compared to outside and the wooden parquet floor in the hallway was covered in condensation as was the Lino floor in the kitchen and the tiled floor in the utility room. I googled and read that if rain gets through to the insulation the insulation effectively carries the moisture across to the interior wall and this causes condensation. Basically once the insulation is wet it's going to damage rather than help the house. Does this not tie in with your knowledge/experience?

Is there a leaking pipe under your house?

It's not a leak. The utility room is connected to the kitchen but is nowhere near the hallway. It's a big house. I'm concerned areas were missed or that the rain has come through over the past few weeks and we now have wet insulation

Also the Lino is not wet underneath just a layer of what seems like condensation on top

I've read that cavity wall insulation can exacerbate condensation by increasing the temperature differential between inside and outside thus leading to more moisture forming on cool surfaces.
Also, it's possible they may have blocked up some of your ventilation with the cavity filler.
Ventilation of itself is not a solution as if you have too much ventilation in an attempt to equalise the internal and external temperatures then your house will just be bloody cold!!!
What you need is very good barriers between internal heat and external cold (so that you don't get condensation) and specific forms of ventilation which aid in extracting moisture from the atmosphere - not just letting great big wafts of cold air in.
If you've overnight and with no previous occurrence, just found water on the floor - a leak is probably more likely than condensation - you would have had condensation in the winter if you were to experience it now.

I am not saying it is a leak in your case, but when we had a burst pipe under the kitchen floor (tiles) the entire house was suddenly covered in condensation.

if the outside wall is cracked or there is a leaking downpipe or gutter, then the outside face of the wall may be wet after rain. Although the cavity insulation is water repellent (dip a bit in water and see) it prevents air movements and draughts inside the cavity, and that means a wet wall will not dry so quickly. In this case find and fix the source of the water.

The water-repellent insulation does not carry water unless it is immersed, and is non-absorbent so it drains quickly.

Water vapour is lighter than air, so it rises to the top of the house. It is extremely difficult to get condensation on a floor (unless it drips off the ceiling or you have a cold-store below). Sometimes a puppy is involved.

Wet floors are almost invariably due to leaking pipes. Sometimes from radiators or bathrooms above, more often from pipes below or embedded in the concrete. Concrete is absorbent so the damp patch may be observed some distance from the source.

To identify if a damp patch on a wall or floor is condensation, tape a piece of clear plastic tightly to it. Condensation will form on the outer (room side) of the plastic which is in contact with the air. Moisture from the wall or floor will appear on the side of the plastic in contact with the wall or floor.

Oh that's a good tip I'll do that later and will Investigate thoroughly and report back. Thanks everyone.

vivandtom
I've read that cavity wall insulation can exacerbate condensation by increasing the temperature differential between inside and outside thus leading to more moisture forming on cool surfaces

Don't agree with this. If the house is humid and suffers condensation, then making the walls warmer will mean that more of it condenses on the windows instead where it is more easily seen. The insulation does not increase the amount of moisture or the amount of condensation in the house, and the walls will now be drier.

Also, it's possible they may have blocked up some of your ventilation with the cavity filler.

Yes, that is possible if the installers were untrained and incompetent, and you had airbricks on the outside and inside of the house with no sleeve. However in this case you would notice insulation gushing into your house through the airbricks.

Ventilation of itself is not a solution as if you have too much ventilation in an attempt to equalise the internal and external temperatures then your house will just be bloody cold!!!

No, condensation occurs due to excessive moisture in the house. To reduce condensation you have to reduce the humidity, either by creating less, or by getting rid of it. People who won't ventilate will get condensation and damp. Verntilation cures condensation by removing the water vapour, not by equalising temperatures.

It's just occurred to me that because the house was literally like a freezer when we arrived home last night we opened all the doors and windows to let in the warm air. Presumably the house is now super insulated which keeps the house cooler in summer and means that when we opened the doors and windows the warm humid air came in, hit the freezing cold surfaces and appeared as condensation ?

how long was it closed up?

Only from about seven thirty in the morning until about five in the evening but it was literally like walking into a freezer. The cold air hit as the front door was opened. The house is so cold that had the doors and windows not all been open all evening I would have needed to have the fires and heating on despite the fact that it was warm outside until really late.

leaking water main.

have you got a water meter?

If not, have you got an outside stopcock and someone with good hearing?

PigletJohn

The insulation increases the temperature of the house, increasing the amount of water which evaporates, which then condenses on the windows hence more condensation.

If there were no difference between internal and external temperatures there would be no condensation on the windows (cool area).

There are of course, ill-traine and incompetent installers of insulation. It does not come out of the air bricks (which are often below floorboard level) in the manner of a foam party as you imply - it bungs up quite quickly.

I don't think you really understand where the moisture in the air comes from and how to remove it.

The insulation increases the temperature of the house, increasing the amount of water which evaporates

No, that could only happen if the insulation caused more water to occur. It doesn't. The water vapour that occurs from breathing, washing, boiling kettles and draping wet clothes around the house is unaffected by insulation. BTW insulation does not have to increase the temperature of the house. It decreases heat loss, enabling the occupants to keep it at the same temperature as before, but at lower cost. However it does mean that the walls will not be so cold, and so they will be drier, because they will not suffer so much condensation.

which then condenses on the windows hence more condensation.

Prior to insulation, the walls would have been colder, so more water would condense onto the walls. After insulation, almost all the condensation occurs on the windows, as they are substantially colder than the walls. Condensation on windows is immediately visible and obvious.

I don't think you really understand where the moisture in the air comes from

yes I do.

The cavity wall insulation will help to keep the floor cold in the same way as it keeps the air warm in winter, so when the temperature changes rapidly when the door is opened and a wall of warm moist air rolls over the cold floor condensation will form on the surface. I would expect that you've got a concrete floor slab, they take a lot of heating up when the seasons change so it might do it for a few more days, you can speed it up by letting the sun on it possible or just leaving the door open when you're in, it will continue to form condensation until it warms up enough to get past the dew point, so what out for a slippy floor. It's a feature of the weird weather we've been having ( with the temp going up 10 degrees in a coi

.....Couple of days) rather than the cavity wall insulation itself.

(damn phone!)

^I don't think you really understand where the moisture in the air comes from

yes I do.^

No. You don't.

Not all water in a house evaporates and then condenses - how could you really think this?
Obviously the insulation cannot cause more water to occur - duh!!!

Assuming you have a fixed quantity of water in a house.
What will cause the water to evaporate? Heat? Without heat there will be no evaporation or condensation. What will cavity insulation affect in a property - heat?

Given that not all water available in a house evaporates at any given time, if you increase the heat - will the same amount of water evaporate, or more or less?

By the way, if you stop adopting a mocking, sarcastic, know-it-all attitude - so will I.

First thing is to dry out the damp you have now. Open the windows, put the kitchen and bathroom fan on etc.

Then see if it reoccurs.

Do you have a crawl space under the ground floor? Is that insulated? If not the ground floor could be the coldest element in the house, compared to the insulated walls and double glazed windows, and as such will be where the condensation forms.

If it's a recurring problem then you'll have to find a way of increasing the ventilation again.

sorry vivandtom I don't understand your point.

And if it doesn't go away in a week start looking for a leak like the other say up thread.