roof + windows + condensation - what specialist do I need?

aoleks

hi all,

I need a bit of guidance on a small issue that I want fixed asap.

we recently moved into our first home and within a few days, we start noticing something. in the morning, when we wake up, there is condensation on the windows and on one occasion, it was also present on the ceiling. the house is fully renovated, everything is new and has been empty for at least 6 months. there were no issues when we moved in, which leads me to believe it's something we're doing (cooking/washing/drying clothes etc.).

central heating (combi boiler) is on all the time, on 20 degrees. radiators have TRV valves, they're all set on 3. hob extractor, unfortunately, is not connected, so it only recirculates the air.

one particular thing that concerned me was one evening when we had a lot of guests, we washed a lot, we dried some towels on the radiators etc., we noticed dripping water from the corner of the ceiling in one of the bedrooms. I know it's not a leak because as I said, the house has been empty for many months and the paint was perfect when we moved in. it only happened when the humidity became too much, it's probably a cold spot from the roof (feels much colder than the rest and is not drying properly).

1. what kind of a survey do I need? damp specialist? ventilation?
2. do I call a roofer to (re)insulate my loft or do I need someone else?
3. should I insulate the loft floor or the roof as well?
4. other than opening some windows and getting a dehumidifier, what can I do to prevent this from happening?

thanks

grumbler

aoleks said:

the house is fully renovated,

This means nothing. Renovations are often done on the cheap, especially before selling. Walls of old houses are very expensive to insulate well enough.

 there were no issues when we moved in, which leads me to believe it's something we're doing (cooking/washing/drying clothes etc.).

The temperature was higher and there were no sources of humidity inside, including breathing people. Condensation on the windows (glass panels, double-glazed supposedly) means just that the air is very humid inside.

 hob extractor, unfortunately, is not connected, so it only recirculates the air.

Well, combined with a gas hob this means a significant source of moisture. Burning gas converts to CO2 and H20.

one particular thing that concerned me was one evening when we had a lot of guests, we washed a lot, we dried some towels on the radiators etc., we noticed dripping water from the corner of the ceiling in one of the bedrooms.

Hardly a surprise. Drying washing inside IMO is absolutely unacceptable, especially in cold seasons. Dry it outdoors or get a drier. Condensation on the ceiling means poor insulation in the loft that you can improve without any 'specialists'.

Doozergirl

As above. 

Take a look at what insulation you have above, if any...   if it's rockwool type insulation in a traditional loft, you should have 300mm of it.  

Then open up all of the trickle vents on the windows. Do they have them?  If not, you can use the night latch setting.  

Make sure you use extractors when showering, a humidity sensing fan is best as it will keep running until the humidity is at a normal level. 

Make sure that your cooker extractor is extracting to outside, not just recirculating.  

You don't really need a specialist or a survey. Condensation is caused by cold surfaces and too high a moisture content so you improve insulation and ventilation. The ventilation issues above are those required by building control in a regular house.  Insulation, you just put as much as you can in a house but remember not to seal the house up so much that it can't breathe.  

Bendy_House

aoleks said:

 in the morning, when we wake up, there is condensation on the windows and on one occasion, it was also present on the ceiling.

central heating (combi boiler) is on all the time, on 20 degrees. radiators have TRV valves, they're all set on 3. hob extractor, unfortunately, is not connected, so it only recirculates the air.

1. what kind of a survey do I need? damp specialist? ventilation?
2. do I call a roofer to (re)insulate my loft or do I need someone else?
3. should I insulate the loft floor or the roof as well?
4. other than opening some windows and getting a dehumidifier, what can I do to prevent this from happening?

thanks

Condensation on the windows is no great surprise, as this will usually be the coldest surface in the room. Cond on the ceiling is not good, tho', as the ceiling should be reasonably well insulated, usually with typical loft insulation.

So the first thing to do is to go up there - assuming you can - and having a good look. I suspect that the corner where the condensation was forming will be both lacking in insulation, but also in the path of a very cold draught from the roof eaves. So that section of ceiling will be sitting at whatever your outside temp is at the moment - 6-odd degrees C?

Please report back with what you find. Please note - this 'draught' in the loft is very important and you should not try and prevent it by stuffing the eaves with loft insulation. Instead ensure that the top of the ceiling is nicely covered up to the tops of the joists, and then a further layer on top running in the opposite direction - but pressed down to still let air flow from the eaves.

If the ceiling is hard to insulate from above, then you could consider having insulated p'board added to the underside - even a 35mm layer will be extremely effective. This will almost certainly do the job, and insulated p'board is effective stuff, and the layer will be on the underside where it'll have maximum effect too. But, this will be far more costly.

It may be you can achieve effective results by using rigid insulation on the top of the ceiling as well, instead of the 'wool' type loft insulation, but you might need advice on that so that there isn't a small void left between the ceiling and the insulation where cond could form.

You say you have the temp at 20oC 'all the time'? I presume you don't mean overnight as well? I presume the heating is turned down at night? That is sensible, of course, but is also why you get cond forming at this time. Warm air (20oC) can hold a lot of the moisture that's formed by normal living processes - cooking, washing, breathing, etc. - but as the air cools overnight, it cannot keep this moisture in suspension, so it instead finds the coldest surfaces to condense out on - ie windows. This is normal. The solution is to ventilate that moisture away...

This means an even chillier bedroom, but then that's why gawd gave you duvets and warm bodies to cuddle. You can test this easily - by all means have the heating on until near bedtime, so the bedroom is nice and welcoming. But, just before jumping into bed, crack open the windows - at least 2 - to 'vent' setting. Yes, overnight, the room will be chilly, but you shouldn't be. Yes if you need to get up for a pee, it won't be as pleasant, but tough. In the morning, the heating will come one before you get up, so it should be fine. Once awake, close the windows, and admire how cond-free they are.

'Other than opening some windows...'? Well, yes, you could use a dehumidifier, by why have an ugly whirring machine running when the obvious solution is to crack open a window or two?

Priority, tho', must go to insulating that ceiling. The best way should become clear when you go up there for a look. Take some photos and report back?

aoleks

hi all,

thanks for all the responses, very helpful. a couple of findings:

1. I went into the loft, it should've been properly insulated and I'm sure it was at some point. what happened though is that the builders installed spotlights and a few other things, for which they needed access to the loft. they removed the insulation and threw it somewhere else, leaving parts of the ceiling "uncovered".

2. I have made a few changes to the central heating, programming the boiler to only hear in the morning, before we wake up (21) and in the evening, before we get home. at night, it's now set on 18 degrees.

3. I bought a unibond dehumidifier (non-electric), that's currently being carried around the house one day at the time, to catch extra humidity. works quite well, but the windows still have condensation on the edges in the morning, I guess I'll never be able to get rid of that.

I found a local company with extremely good reviews that can transform the loft completely, it basically becomes a room (not a conversion). I am thinking to hire them to place proper insulation on the floor and between the joists, board the loft and plaster it all over. I will also bring someone in to connect my extractor to the outside.

Bendy_House

aoleks said:

hi all,

thanks for all the responses, very helpful. a couple of findings:

1. I went into the loft, it should've been properly insulated and I'm sure it was at some point. what happened though is that the builders installed spotlights and a few other things, for which they needed access to the loft. they removed the insulation and threw it somewhere else, leaving parts of the ceiling "uncovered".

2. I have made a few changes to the central heating, programming the boiler to only hear in the morning, before we wake up (21) and in the evening, before we get home. at night, it's now set on 18 degrees.

3. I bought a unibond dehumidifier (non-electric), that's currently being carried around the house one day at the time, to catch extra humidity. works quite well, but the windows still have condensation on the edges in the morning, I guess I'll never be able to get rid of that.

I found a local company with extremely good reviews that can transform the loft completely, it basically becomes a room (not a conversion). I am thinking to hire them to place proper insulation on the floor and between the joists, board the loft and plaster it all over. I will also bring someone in to connect my extractor to the outside.

Tsk - some builders are twits :-)  Mind you, if the spotlights have halogen lamps in them, these get very hot so they may have wanted to keep insulation off them to prevent overheating. Ideally you pop a firehood over each one, and then you can lay the insulation tight up against them again. Or, better still, replace with LED, and relay the insulation fully as before.

By all means get a quote for the 'loft conversion', but I bet it won't be cheap. And it'll only be a storeroom?

I'd get a quote for just laying down the full recommended level of loft insulation as it stands, and then leave that loft as it should be - a cold, draughty but dry storage space. But that's your call.

You will continue to have cond on your windows in the morning if you don't ventilate it away overnight. Almost certainly. Yes, you can instead try and draw that moisture out using a dehumidifier and that will also work provided it's effective enough. Tbh, a bit of cond on the panes in the morn isn't the end of the world - just wipe it up with a cloth each morn, and allow the room to ventilate. It's when it becomes extensive, and/or cause mould to form on the surrounding walls and ceilings - that's when it's gone too far.

Rdwill

Have you considered Positive Input Ventilation

We have a Mr Venty from Envirovent, he was the predecessor to their atmos machine

https://www.envirovent.com/products/positive-input-ventilation-piv/atmos/

And i can not praise it enough for controlling condensation and giving the house a fresh 'airy' feeling.

Phil4432

Haven't read the replies so maybe I'm repeating what's already been said...

Perfectly normal to get condensation, due to the effectiveness of modern windows.  But you want to reduce it by as much as possible.

The house must be heated to at least 14C, open all the windows for at least an hour/day and get a dehumidifier. 

You mentioned a unibond non electric, not sure how that works but you need one powerful enough to deal with the whole house, not individual rooms.   I have a larger ebac 2650e, does the job well but prone to breakdowns.  It has the extraction rate you'd need for a 3/4 bed house.

Drying towels or clothes on radiators should be avoided.  The dehumidifier I mentioned has a laundry mode which works ok.  But always best to dry clothes outside as much as possible.

Open a window when bathing/showering even if you have an extractor.  Keep the bathroom door closed.  Same with the kitchen while cooking.  Open the bedroom window first thing in the morning.

That'll probably solve it.

grumbler

Phil4432 said:

 open all the windows for at least an hour/day and get a dehumidifier. 

In winter? - No chance!  And I don't have a dehumidifier.

I do open slightly a window in the bedroom at night and, sometimes in the bathroom - fully, but, of course, not for an hour.

jamesd

Not sure it's been explained yet but you get condensation when the temperature on some surface falls below the dew point of the air next to that surface. This temperature is higher when the moisture content of the air is higher and lower when it's lower. Raising the temperature of the surface also makes it less likely that you'll have condensation on that surface. All the possible remedies involve reducing the amount of moisture in the air and raising surface temperatures.

Major sources of moisture are cooking and washing and if done inside without a condensing drier, drying clothes. So to address those at source:

1. Install a humidity controlled extractor fan in the bathroom where most showering takes place. You can then do air drying inside in that room as well because the extractor will keep the humidity under control. It's useful to have the door closed and draught proofed for this. If it is, you can open a window in the room to help as a test and without making the whole house cold. Fan installation will probably cost a few hundred pounds, draught proofing the door ten or so with leftovers for other doors, so try door draught proofing and window opening for a while as a cheap and easy start on this water source.

2. Yes, getting the kitchen extractor working to the outside so that it'll take cooking moisture out of the building is a good move. A similar initial approach to the bathroom is possible, door to the kitchen shut and draught proofed with a window open for a while to get rid of the moisture-laden air. Again, not permanent but it'll prove the method of getting rid of water at its source.

3. Humans are another major source of moisture. Trickle vents should be enough to deal with this one.

Now, surfaces.

4. Secondary double glazing film on the inside of the windows will make a warmer surface so condensation is less likely to form on that than on the glass. Cheap and easy, Wickes is one DIY place that stocks it. It'll probably increase room comfort as well as saving a little energy. Put a bit of the dehumidifying crystal material between the glass and film in some sort of tray immediately before applying the film to remove the existing moisture that would be trapped between glass and film.

5. The early hours of the morning are when the temperatures are coldest. A bit of heating for a little while can prevent the surfaces getting so cold and reduce or stop condensation.

6. Gaps in insulation are bad news because the heat flow ends up concentrated at the gaps. So the loft needs to be sorted out to have a continuous layer of insulation. There are spacers that ensure air can flow from the ventilation holes in the eaves into the attic space above the insulation to prevent damp up there. You must ensure that there is ventilation above the insulation or water can condense on the insulation, making it useless and potentially leaking into the ceiling below. A burst of heating in the early hours if 1 and 2 don't get rid of enough water a source is a temporary remedy for this condensation on the ceiling.

That should at least let you get started with a few cheap and easy partial remedies before getting on with the more expensive and troublesome ones.