Drying Out Times

Calluna

We're currently building and I just wondered if anyone had advice regarding drying out times and methods - I've had a look in this forum and the advice re floor screed seems to be 1 day per mm. The house is being roofed at the moment and windows are ordered. If plastering was taking place during the month of October, how long should you leave it to dry?....I've also had advice that air drying is better than having the heat on in the house....

We're not having underfloor heating, house is 2,800 block built - 4inch kinspan in 6 inch cavity, two storey, hollecore so block first floor walls, not dry lined. Not sure what other info you need, sorry - we are new to this. West of Ireland - possibly more rain than other areas...in theory, although this summer!
Obviously we don't want cracks, etc, or worse? Any advice is welcome. Thanks

ircoha

Very difficult to give a precise figure as the key element here is what relative humidity will prevail during the drying out period.
The damper the air, the less the drying so rather than use heating to raise the air temp and therefore allow it retain more moisture vapour, and therefore assist in the drying, you might rent a dehumidifier to reduce the relative humidity in the 'cold' air in the house and thus promote drying without having to heat the house and thus reduce the risk of drying out cracks.

If you go this route ensure that the water which the dehumidifier will produce can flow freely out of the house/ some people put them in the bath.

They can vibrate a bit and move so make sure it is well held
If the one you rent has a water collector u will need to empty it out on a regular basis.

Rest assured however that they do work well. Had a underfloor leak in a new build that only became apparent when the water started coming up the walls over the skirting boards.

Used a dehumidifier for 2 weeks, worked really well

sinnerboy

If you wet plaster the walls - allow 4 weeks min . Either invest in a good damp meter (€400 approx) or hire one - ( €30 per approx ) . Avoid fixing skirting etc untill you get a good reading . Wet plaster will tend towards a better air tightness vs plasterboard on dabs or battens .

If you are using plasterboard on dabs or battens you will need less time for it to dry out obviously - however - avoid trapping moisture behind - the block work and mortar . ( Again , damp meter )

As for floors - 1 mm per day . If you can afford time - it is best to use it . If not dehumidifiers can be good .

If you can still reach them - plug you hollow core voids at the ends with a mortar pack and grout the soffit joints ( to improve air tightness ) . Extend your plaster finish tight to the concrete i.e. that strip of wall that will be hidden by the ( assumed ) battened down ceiling - plaster it too .

Also - if you can € it - consider insulated dry lining . More insulation the better is rule no 1

pete6296

Hi,
1mm per day for floor screed to dry, would that mean a total of 75 days for a 75mm floor screed. Seems a long time.
Pete

sinnerboy wrote: »

If you wet plaster the walls - allow 4 weeks min . Either invest in a good damp meter (€400 approx) or hire one - ( €30 per approx ) . Avoid fixing skirting etc untill you get a good reading . Wet plaster will tend towards a better air tightness vs plasterboard on dabs or battens .

If you are using plasterboard on dabs or battens you will need less time for it to dry out obviously - however - avoid trapping moisture behind - the block work and mortar . ( Again , damp meter )

As for floors - 1 mm per day . If you can afford time - it is best to use it . If not dehumidifiers can be good .

If you can still reach them - plug you hollow core voids at the ends with a mortar pack and grout the soffit joints ( to improve air tightness ) . Extend your plaster finish tight to the concrete i.e. that strip of wall that will be hidden by the ( assumed ) battened down ceiling - plaster it too .

Also - if you can € it - consider insulated dry lining . More insulation the better is rule no 1

RKQ

pete6296 wrote: »

1mm per day for floor screed to dry, would that mean a total of 75 days for a 75mm floor screed. Seems a long time.

Not really, got to allow slab to dry too, so add 100 to 150 days.
(It used to be 1 month per inch for a 6 inch slab)

The longer the better IMO.... hate to see a beautiful solid timber floor twisting and cupping... so expensive to replace!

Dry timber is like a sponge on a damp screed / slab... Moist timber will move and twist, guarenteed.

Give it time, especially with this damp wet weather.

Calluna

I thought it was a long time too...but hey, this is the 'forever' house so it's best get it right. As a matter of interest does the same apply for tiles and semi-solid/laminate - would they be (as) affected too?
It's likely we'll be going the dehumidifier route - looking like house will be closed in and plastering starting in about a month so then you're talking end oct/nov/dec - which prob aren't ideal for drying from a humidity point of view and given the weather we have been having.
Thanks for the feedback - I was just a little concerned because our builder said that we could be 'in by christmas' but bro in law told me he left his to dry naturally to avoid cracks. Didn't know about the dehumidifier at that point - but have been talking to builder since, and the dehumidifier is the plan at the moment. We'll see about the christmas deadline, but he has been using it with subbies to date - we aren't too pushed (well, don't want to get my hopes up I suppose).
Thanks again