Dehumidify or not?

sas

Hi,

Plastering started on monday. House is very very damp.

A little concerned about my timber windows due to the level of condensation on them.

I am in no rush to dry the place out and will be leaving the windows open. Granted, with frost last night it will not exactly be hugely effective.

However, I'm wondering if I could safely (i.e. not crack plastering due to force drying) run a dehumidifier to keep the moisture level down.

Thoughts?

MicktheMan

Sas,

what I would suggest is supply some heating to the house and leave the windows slightly open. This will allow the house to ventilate (read dry out) naturally and slowly reducing the risk of plaster cracking. A couple oil filled thermostatically controlled rads set up to keep internal temp at 16/17 degC might work for this.
The warmer internal air will take up the moisture and be replaced with dryer external air. The colder it is outside, the better your house will dryout naturally.
(I'm assuming here that your mvhr system is temporarily sealed up and not yet commissioned)

zom

My builders friends always use dehumidifiers when plastering (big "industrial" ones). I presume they don't like to have cracks on plaster they do so I think it's safe in that matter. Heating up the house can make moisture to penetrate walls/floors instead of removing it.

Carlow52

zom wrote: »

My builders friends always use dehumidifiers when plastering (big "industrial" ones). I presume they don't like to have cracks on plaster they do so I think it's safe in that matter. Heating up the house can make moisture to penetrate walls/floors instead of removing it.

Not if its ventilated as stated by MM

tred

Carlow52 wrote: »

Not if its ventilated as stated by MM

Key if your using dehumidifers is to move them around. My brother left one in the same place for a long period, and the ceiling skim started cracking in just that room. Heat needs to be left on Low as well, not too high. I had a ventilation system in place at this time, so that assisted my drying big time.

sas

Quick update. The house is drying well. The plastering has not caused anything like the level of condensation that I feared.

I am chalking at least some of this down to our passive specification.

We leave a couple of windows tilted at night. Naturally during the day more of them are open as are doors which helps keep things drying.

The mild weather is likely contributing too.

sas

Was on site on saturday morning. Granted it was down around 0 degrees over night. The windows were all saturated inside. Some of the plaster on the window reveals is showing signs of having soaked up some of the moisture i.e. it's gone dark again.

We've had 2 2kw oil rads on constantly since 24th Dec. Windows left open upstairs at night for cross ventilation.

They helped but not enough it would appear.

Dehumidifer was turned on at 1.15pm on saturday. By 3:30pm on sunday it had collected approx. 10 litres. Hard to tell if this is alot but the windows weren't wet anymore. I'm collecting the water so that I dcan tell if the rate of collection is reducing i.e. are we actually drying out the building.

Is 10 litres in 24 hours alot?

On the plus side, the 2kw rads appear to be capable of heating the house. The attic in particular was what you would describe as "hot" on saturday morning. Considering the place is still damp and unocuppied, it would appear we are at least getting there.

creedp

sas wrote: »

Was on site on saturday morning. Granted it was down around 0 degrees over night. The windows were all saturated inside. Some of the plaster on the window reveals is showing signs of having soaked up some of the moisture i.e. it's gone dark again.

We've had 2 2kw oil rads on constantly since 24th Dec. Windows left open upstairs at night for cross ventilation.

They helped but not enough it would appear.

Dehumidifer was turned on at 1.15pm on saturday. By 3:30pm on sunday it had collected approx. 10 litres. Hard to tell if this is alot but the windows weren't wet anymore. I'm collecting the water so that I dcan tell if the rate of collection is reducing i.e. are we actually drying out the building.

Is 10 litres in 24 hours alot?

On the plus side, the 2kw rads appear to be capable of heating the house. The attic in particular was what you would describe as "hot" on saturday morning. Considering the place is still damp and unocuppied, it would appear we are at least getting there.

I've an ongoing issue with condensation on windows even though house was plastered last March and floors poured in July. Now the amount of moisture is minimal and concentrated only along perimeter of glass especially at bottom of panes. However, it doesn't seem to be going away. Its worse when the temps drop .. for instance the last couple of days have been more noticeable again while there was very little to be seen over the previous couple of mild weeks. I moved into house in November but prior to that elected to leave house dry naturally .. maybe this was a mistake! I have MHRV and when set at normal setting the condensation was worse so I asked for the setting to be upped and this certainly has helped but not eliminated the problem. Im keeping the fingers crossed that its just a drying out issue and will resolve itself over the next few months.

BryanF

creedp wrote: »

I've an ongoing issue with condensation on windows even though house was plastered last March and floors poured in July. Now the amount of moisture is minimal and concentrated only along perimeter of glass especially at bottom of panes. .

what is the frame specification, it amy that moisture is forming on the cold frame.. might be worth doing a thermal imaging test - maybe getting your window manufacture/installers to do it.. installing an RH sensor or two would be useful to figure out where the moisture is originating form..

sas

creedp wrote: »

...and concentrated only along perimeter of glass especially at bottom of panes.

This is what I have been seeing normally too. Last night I visited site and everything was noticeable drier but the bottom 2 corners of each window had some condensation and the timber bead along the bottom had droplets on the frame.

Now my house only had screed poured on 17th Dec. along with a week of plastering after that. So I'm not panicing yet, especially as the house was clearly drier due to the dehumidifer.

There should be nothing wrong with the spec. on my frames i.e. PHI certified.

tred

sas wrote: »

This is what I have been seeing normally too. Last night I visited site and everything was noticeable drier but the bottom 2 corners of each window had some condensation and the timber bead along the bottom had droplets on the frame.

Now my house only had screed poured on 17th Dec. along with a week of plastering after that. So I'm not panicing yet, especially as the house was clearly drier due to the dehumidifer.

There should be nothing wrong with the spec. on my frames i.e. PHI certified.

SAS, take as much opportunity if the weather permits to open windows and doors and let it dry that way. It might not be as easy if no one about. Cant beat that for drying either

sas

tred wrote: »

SAS, take as much opportunity if the weather permits to open windows and doors and let it dry that way. It might not be as easy if no one about. Cant beat that for drying either

We've been doing this as and when someone is on site.

I had thought the place was doing well. We'll see this evening how much has been collected over the last 24 hours.