Too much loft insulation?

We live in a 1930’s stone built semi with plastic windows.

Woke up this morning and all the upstairs windows are covered in condensation. This is despite most of the upstairs windows being left open on the ‘notch’ section ie about a 1cm gap but still locked.

About 4 years ago I increased the loft insulation to x 2 20cm thick layers. Is it now preventing moisture escaping?

What else can I do?

Ta

Check to make sure the eves are ‘ventilated’?

As above. Make sure the insulation isn’t rammed right into the corners blocking the air flow up there. TBH it’s an old house so I’d expect a bit of condensation.

About 4 years ago I increased the loft insulation

Why has it taken 4 years to have any effect – it’s more likely down to a drop in temperature overnight as tends to happen this time of year.

Read this it might be informative:

http://www.telegraph.co.uk/property/propertyadvice/11123348/Home-improvements-how-can-we-stop-condensation-on-the-windows.html

The risk of ‘too much’ insulation in the loft is condensation within the insulation itself making it wet with resulting loss in effectiveness and possible staining/timber decay.

Insulation in the loft will only cause condensation in the sense that the air in the house will be slightly warmer & therefore able to hold more moisture which will condense when it hits a cold surface. The cure is usually to make sure the extract ventilation in the kitchen & bathroom where the majority of moisture within the air of houses originates (and to make sure the ventilation is used).

The bottom line is that moisture in the air will find somewhere to condense as long as there are cold surfaces within the house

The insulation is right in to the corners, how much gap should you leave, and what does it do by leaving a gap?

The problem has been there for some years. We are actively leaving windows open to try and make more difference, but it hasn’t..

We also get mold building on external wall surfaces.

Depends on the design of your roof – I doubt a 1930’s semi had eaves ventilation.

“We also get mold building on external wall surfaces.”

and did you have this before ?

I put the insulation in when we moved in to the house, so yes since, but it was an old couple who lived there before who only boiled a kettle, not a young family.

I doubt a 1930’s semi had eaves ventilation.

Mine did… Could be a later change of course.

It was significantly colder last night so chances are the temperature within your house dropped further than it has of late.

The colder the air gets the less moisture can be contained, instead it condensates on the coldest spot within a room, usually the windows but can also sit on exterior walls and this is where the mold will form.

The key is ventilation, especially in old houses, they need to breath, unfortunately the more you insulate (loft, windows, doors etc) the worse the problem gets.

Do you dry your washing on the radiators too?

Having recently moved into a 1930s house and having the loft and walls insulated. Im following this with interest.

We have a noticeable problem with condensation imo. However i do have a question how do you guys dry your clothes etc in the house without a tumble dryer. Recently we have to bring our washing inside as its getting chilly and the condensation is terrible. We have extractor fans in the kitchen and bathroom but wherever we dry stuff we end up with wet walls. How do you get around this?

Ventilation is the key.

First thing is to get rid of moisture at source (kicthen / shower extractor).

We’ve then had good results with positive pressure trickle ventilation, especially with regard to mould etc. Google Nuaire Drimaster or Xpelair Everdri. They are a fairly cheap and simple option.

I’ve also experimented with heat recovery ventilation but don’t think it is very effective unless designed into the home from the start.

andy brad – dehumdifier is your friend.

lower energy use than the tumble dryer – all the condensation is captured.

Yup, 1930’s house here and loads of condensation on the single-glazed windows on a cold morning. Solved by using a dehumidifier, venting bathroom and kitchen as much as possible.

We do have an air extractor in the kitchen, which to be fair we disconnected as it appeared to constantly run regardless of whether anything was happening, even though it can apparently be adjusted for humidity setting.

We also disconnected the one in the bathroom as it was operated as soon as a light was switched on, which is v annoying! (next to living room)

Will note and put the kitchen one back on.

So will moving the insulation back where the floor meets the roof make any odds? If it helps the roof extends down beyond the edges of the loft space.

We have a dehumidifier but its big and noisey 🙁

Clothes are dried outside or in a tumble drier.

Mick r – I assume the unit sits in the loft above the stairway ? Any you create a hole in the ceiling?

Cheers

I doubt a 1930’s semi had eaves ventilation.
Mine did… Could be a later change of course.

As does ours. And pretty much every one I’ve ever been into the loft of.

It was significantly colder last night so chances are the temperature within your house dropped further than it has of late.

This – it was frosty early this morning for us (Harrogate). All our upstairs windows were very wet this monring – first time this year.

put the bathroom one back on as well – there will be more condensation coming from your shower than your cooking ill bet. just plumb the fan into a second switch if you really cant live with the noise for a few minutes while someone takes a leak.

“we disconnected as it appeared to constantly run regardless of whether anything was happening, even though it can apparently be adjusted for humidity setting.”

that tells me either its **** or more likely by your symptoms – your humidity is high.

glad we got to the bottom of that as is the norm with most damp cases its down to occupants.

Woke up this morning and all the upstairs windows are covered in condensation.

We do have an air extractor in the kitchen, which to be fair we disconnected…

We also disconnected the one in the bathroom…

I think we have identified the root of the problem…

I had a free survey from British Gas as a tenant complained it was cold. BG did a survey of the loft & insulation foc, I think it was part of a green initiative.

Get them to have a look, the property doesn’t even have gas & we have no connection with BG.

Joking aside, you are putting moisture into the air (breathing, persperation etc.) and the house is now significantly warmer than when it was designed (due to your fancy windows and insulation). Unless you remove the moisture or reduce the temp difference you will get condensation on the windows.

Pulling back insulation will likely do nothing for the explained problem, but is a good idea to prevent issues in the loft.

I have just finished a renovation on a 1920’s semi and am getting some condensation on the windows (and a considerable amount this morning). Prior to the work it was not as bad, due to draughts, air gaps and less insulation, but the house was colder and draughty, so no surprise there.

Lady takisawa2 was complaingin yesterday, that the South Wing was smelling & feeling a tad damp. (1960’s ex Council semi of solid wall construction)
She does every year at about this time.

I put it down to it not quite being cold enough inside for the heating to come on, but the outside dipping sharply during the night. As soon as the heating starts coming on it goes away.

Was a lot worse before we had the walls externally insulated.

Ventilation is usually the solution in the majority of condensation issues IMHO.

As above PIV might be the solution if you’ve exhausted other avenues.

We live in a 50/60’s house, the owners we bought it off have done a fair bit of DIY – in the process removed all forms of ventilation air bircks/no trickle vents/ no bathroom extract etc.

In cooler weather there would be alot of condensation in all upstairs windows, pools of water on cills, mould forming on blinds and cornerjunction of walls and ceiling.

I was sceptical but had one of these installed:

http://www.envirovent.com/home-ventilation/products/condensation-and-mould-solutions/mr-venty-eco-sub-2-sub-loft/

It has solved all of our condensation issues – yes the bathroom gets condensation when being used etc, but does not linger as before.

I am in no way guaranteeing it will work, it’s not for everyone, some notice a draught (I do not as I’m a burly man grrrrr!) and as with everything look online for these type of systems there will always be those where it did not work.

Was £900 fitted – had it about 2.5yrs now.

Similar topic discussed a while back that may also give some suggestions.

http://singletrackworld.com/forum/topic/help-with-dealing-with-damp-in-a-bedroom

Edit: blimey alot of people have jumped in since JohnDoh whilst I’ve been typing – must type quicker in future 😆

Mick R, just googled those positive ventilation devices, as we have a slight mould issue especially in the least used room (above integral garage, so probably colder). They seem a great idea, what are your experiences? I see some models have a warming option, which seems to make sense to go for? Expensive or noisy to run?

mick_r – Member
…I’ve also experimented with heat recovery ventilation but don’t think it is very effective unless designed into the home from the start.

Often wondered if this sort of thing would work for those who are afraid that PIV will be too cold.

http://www.envirovent.com/home-ventilation/products/heat-recovery-systems/heatsava/

EDIT: and there appears to be alot of scepticism about MVHR and Building Controls finding the real world application is no-where near as good as the manufacturers test……surprise surprise.

all interesting stuff.

Isnt a dehumidifier expensive to run?

we also have a massive issue with water leaking out of the shower door. replaced seals 3 times not and it still does it

andybrad – Member
all interesting stuff.

Isnt a dehumidifier expensive to run?

Whether the answer is yes or no I would suggest it’s not a permanent solution for condensation/ventilation issues.

you dont run the dehumidifer all the time (if you are you have bigger problems) you just run it when you have washing to dry.

its 2-3 pence an hour dependant on the dehumidifier. i set it up in the spare room and clothes dry over night -8hrs

tumble drier – 60 pence a load ? plus the dehumdifier is much smaller than a tumble drier

– also consider that a dehumdifier is actually a pretty efficient heater as a by product.

trail_rat – Member
you dont run the dehumidifer all the time (if you are you have bigger problems) you just run it when you have washing to dry.

Looks like you’re using it as a permanent solution if not running the unit permanently. 😉

A tumble dryer ducted to outside would be better for the building than a dehumidifier although your wallet wouldn’t thank you obviously.

double post

“Looks like you’re using it as a permanent solution if not running the unit permanently. ”

nope you’ll have to explain that one to me ?

i dont have a damp issue i just dont want to cause one by drying clothes in the spare room.

My parents have used the Everdri ones for 30 years and it solved everything in their bungalow, but it is bigger than ours and has no shower – so it was more of a moving air around problem (bungalows are useless at convection).

We only slightly notice ours when it is very cold (Xpelair Everdri). I fitted it in an insulated cabinet in the attic, so have the choice of attic (warmed ish) air in winter and piped in fresh outdoor air in summer (so get fresh air and some ventilation in hot weather even if windows are shut).

On the settings we use it is inaudible. Running costs very minimal. I have considered a small trickle heater but need to do some calcs to see if it would actually do anything. We still have a little condensation when really cold but it is a bungalow (bad airflow), 4 people in a small space, lots of showers etc so pretty much a worst case scenario. Occasionally use dehumidifier if we are dumping a lot of moisture in winter (drying clothes etc). Dehumidifier is more tackling the problem not the cause, you’re still re-circulating stale (but drier) air and can be a bit noisy (better in a house where you can shut it downstairs at night).

In my (unqualified) opinion MHRV was a waste of time and money for my retro fit. To get the efficiency you need a very air tight house. The unit we tried was a bit rubbish (steel casing and no condensate drain = rust). If it was run slow enough to be acceptably quiet then got lots of mouldy black gunk in the heat exchanger and pipes where warm and cold met. Also putting them in the attic (coldest place in the house) is a daft idea. I can imagine they are great if designed into a modern airtight house from day 1 (maybe built inside a warm internal wallspace).

This is a really timely thread for me too. We don;t have condensation issues, but the front (north facing) rooms in our house (a bungalow…) are noticeably damper than the back of the house. And the Nest thermostat in the hallway suggests humidity is often above 65%.

I had considered a dehumidifier, but the Everdri seems like a great solution.

Seriously looking at the Everdri. Looks simple to fit too.

Our house is over 3 floors, so would be interesting to see if it could cope, will contact the manufacturer.

One of my better purchases a dehumidifier. Air somehow feels much nicer/easier/cleaner to breathe and definitely makes for a warmer feeling house for a given temperature. Once it’s pulled the moisture down our Ebac settled to about 1kwh/day, which is what, ~£1/week Oct till March.