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HELP WANTED - Reducing Moisture Level in Floor

PoolDude

Folk's,

I'm looking to get into my house as soon as possible and at this stage almost everything bar the carpentry is done. The ESB connected last week, the Electrician will turn it on this week and the plumber will get the heating going.

I have about 100 sqm of concrete floor to lay solid wood floor on. I'm going to put down Classic Solid Maple from Brooks - with Polythene film and foam underlay (based on the advice I've seen on here).

I had the moisture levels checked last Wednesday and they are at 5% and a little higher in one or two of the rooms. I need to be in by the middle/end of August. I am going to wait until after the floors go down to put in the skirting, doors and fireplaces, so I've got a couple of days work to do after the floors actually go down (which will also take a day or two).

So the question is how do I get the moisture levels down to 3% as quickly as possible (and should a dehumidifier be used).

Thanks

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RebelButtMunch

Definitly use a dehumidifier. I did, and it half filled one of those big white containers, cant remember how many gallons are in them

Bear in mind though, that they only take the moisture out of the air and probably only the top 3mm of concrete. Any mositure under that will need to 'seep' up before the de-humidifier can get at it.

RebelButtMunch

Forgot to ask, are you using a layer of plywood too?

Mellor

The dehumidifier only removes airbourne moisture, and possible surface moisture, but the lower the air is, the quicker the moistre will rise out of the concrete into the air and so on.
As for how long it would take, no idea. Somebody might of used one recently and be able to give a rough idea.

The Hill Billy

When was the floor poured & what is the depth of the concrete?

For what it's worth - A general rule of thumb that I've seen quoted on several sites is that the recommended drying-out period is 1 month per inch of concrete.

PoolDude

Floors were poured at the end of February, I think they are 150mm, so that would be 6 months = end of August.

The Hill Billy

PoolDude wrote:

I need to be in by the middle/end of August.

Looks like it's a tent in the back garden then.

You are best not rushing these things.
Remember that you'll also probably need to let your timber acclimatise to the house conditions. Is the timber in the house now?

PoolDude

No, I was going to wait till next week to order it (after the heating is connected).

PoolDude

Any others tips to speed the process up?

Do-more

Hill Billy wrote:

When was the floor poured & what is the depth of the concrete?

For what it's worth - A general rule of thumb that I've seen quoted on several sites is that the recommended drying-out period is 1 month per inch of concrete.

The rider on that rule of thumb is "for thin screeds" i.e. no more than 3 inches! they also normally state "in ideal drying conditions" and the weather at present is definetly not ideal for drying. Despite being hot the high humidity means that there is little to encourage the moisture to leave the floor.

You could seal the floor with a liquid DPM, although they can be expensive. Normally needs two coats applied at 90 degrees to one another. Talk to Noel in RS Sales on Hannover quay (I'm assuming he's still there, although it's years since I have dealt with him) knowledgeable and helpful.

Alternatively, as your skirting boards are not yet installed you could run your plastic sheeting about 3 inches up the wall, covering it with the skirting so that you are preventing the moisture from effecting your woodfloor. You do have to be extremely careful not to puncture the sheet though (not an easy task). Assuming your moisture test to be accurate there shouldn't be enough moisture left in the floor to cause serious problems.

One thing to do is to tape down a sq. metre of clear polythene sheet in the centre of the floor and see what happens, it's a bit subjective, but by seeing what moisture is trapped under the polythene after a few days you will get a visual impression of what the moisture level in the slab is.

When I was installing my floor it had 8 months drying, I glued the flooring direct to the slab using Gutoid adhesive. Even so I had two small patches which suffered loss of bond after having been laid about 6 months. Not sure if these were due to moisture or from going into the adhesive too late. (i.e. giving the adhesive too much open time) Anyway 4 years on there are no further probs. It's a personal thing but I like the solidity of wood glued to the slab, no hollowness when trafficked. The Gutoid is solvent based and so is tolerent to a small amount of moisture. But don't take my word for it, ask for some technical advice whatever you are buying!

There was a thread a few weeks back on problems encountered with boards left to acclimatise in a room that was too damp, would suggest you have a read of that also.

Johnniep

Do-more wrote:

Assuming your moisture test to be accurate there shouldn't be enough moisture left in the floor to cause serious problems.

I have seen different moisture meters give quiet different results on the same slab so maybe see if you can get your hands on a second meter just to see!

towbar

we are in a similiar boat - floors poured in April but less depth ~3" - we have heat on for 5 weeks though and used a dehumidifer - The first week it was taking out about 20 litres per day by end of second week it was down to about 5 litres - not sure if it would eventually go to zero as we returned the machine last week. We used it to get the mositure down in kitchen before installing wooden units as apparently doors will absorb moisture in the air also.
Also the mix poured for our floors was fairly dry.

Have decided not to take the chance on putting down wooden floors before we move in (also before end of August)- gathering up as much capret cutoffs as we can!! Might chance down a few sheets of plywood in the hall as a base for the floor just before we do move in but I think it will be another month or two before we order the timber as the bedroom floors still dont look fully dried.

bro'

towbar wrote:

we are in a similiar boat - floors poured in April but less depth ~3" - we have heat on for 5 weeks though and used a dehumidifer - The first week it was taking out about 20 litres per day by end of second week it was down to about 5 litres - not sure if it would eventually go to zero as we returned the machine last week. We used it to get the mositure down in kitchen before installing wooden units as apparently doors will absorb moisture in the air also.
Also the mix poured for our floors was fairly dry.

Have decided not to take the chance on putting down wooden floors before we move in (also before end of August)- gathering up as much capret cutoffs as we can!! Might chance down a few sheets of plywood in the hall as a base for the floor just before we do move in but I think it will be another month or two before we order the timber as the bedroom floors still dont look fully dried.

towbar, I seem to recall in another post that you have UFH -I may be wrong? Does it still take so long to dry the floors even with UFH. i am getting my floors poured tomorrow and did not want to wait 4-6months!

towbar

No I dont have UFH - have alot of pipes in the floor though as each radiator piped seperately which is why the hall is dry. I'd say with UFH it should dry out pretty quick but there is probably some guide about how quickly you can apply heat to the floor.

PoolDude

Johnniep wrote:

I have seen different moisture meters give quiet different results on the same slab so maybe see if you can get your hands on a second meter just to see!

Do you recommend a particular meter and where it could be purchased, e.g. e-bay?

Thx.

PoolDude

towbar wrote:

we are in a similiar boat - floors poured in April but less depth ~3" - we have heat on for 5 weeks though and used a dehumidifer - The first week it was taking out about 20 litres per day by end of second week it was down to about 5 litres - not sure if it would eventually go to zero as we returned the machine last week. We used it to get the mositure down in kitchen before installing wooden units as apparently doors will absorb moisture in the air also.
Also the mix poured for our floors was fairly dry.

Have decided not to take the chance on putting down wooden floors before we move in (also before end of August)- gathering up as much capret cutoffs as we can!! Might chance down a few sheets of plywood in the hall as a base for the floor just before we do move in but I think it will be another month or two before we order the timber as the bedroom floors still dont look fully dried.

Did it impact your plaster - I have heard that the dehumidifier can cause the plaster to crack etc and was kinda suggest not to do this by the builder.

Have you tested the moisture in your floor?

towbar

Doesnt seem to have affected plaster - apparently it can but we have a timberframe so its only a skim coat and it was done months ago.

Havent used moisture meter - dont have one - must see if I can hire and test but definitely the two bedrooms on the north side of the house still have a slightly damp feeling to them.

Do-more

PoolDude wrote:

Do you recommend a particular meter and where it could be purchased, e.g. e-bay?

Thx.

IMO the most accurate to use are relative humidity hygrometer type moisture meters, I used to have a Tramex meter a few years back but it went missing! Nearly fell over when I searched the net and found that a new one is $870.

The simple two pronged electric ones are really designed for wood and johnniep is quite right in saying that they are notorious for giving inaccurate results when measuring concrete (that's why I conditioned my original statement by saying "assuming your moisture test to be accurate")

Sorry I don't know where you could rent one but you could ask Karlam Ireland Ltd. 69 Merrion Road, Dublin 4, Ireland. Phone: +353 (01) 269 4217 if they know, as far as I can remember, that is where I bought mine about 10 years ago.

dingding

I have a wide plank oak floor that has cupping. i.e. The edges of the plank have raised up.:eek:

Any ideas what I can do. Is the floor permanently damaged.:(

Thanks

Mellor

dingding wrote:

I have a wide plank oak floor that has cupping. i.e. The edges of the plank have raised up.:eek:

Any ideas what I can do. Is the floor permanently damaged.:(

Thanks

have the floors be laid or are they still in the pack.
If they are laid theres little you can do, sanding will reduce the look of it.
If they are in the pack, try to return them, if you cant then id buy more

PoolDude

I got the same moisture meter as Yop on e-bay and took reading on a couple of days this weeks and it comes in around 3%. To be sure I have soemone coming fom one of the local suppliers to check it with there equipment.

PoolDude

Do-more wrote:

Alternatively, as your skirting boards are not yet installed you could run your plastic sheeting about 3 inches up the wall, covering it with the skirting so that you are preventing the moisture from effecting your woodfloor. You do have to be extremely careful not to puncture the sheet though (not an easy task). Assuming your moisture test to be accurate there shouldn't be enough moisture left in the floor to cause serious problems.

How much protection will this give?

As I mentioned, my e-bay purchased moisture meter (same as the one Yop got) shows 3% but i am waiting to see what the fitters meter says.

I'm buying from Brooks and interestingly enough their brochure says 'the moisture content must be no more than 5%'

Do-more

PoolDude wrote:

How much protection will this give?

As I mentioned, my e-bay purchased moisture meter (same as the one Yop got) shows 3% but i am waiting to see what the fitters meter says.

I'm buying from Brooks and interestingly enough their brochure says 'the moisture content must be no more than 5%'

Hi PoolDude There are a few points here, firstly laying a good damp proof membrane (plastic sheeting) will provide excellent protection for your wood floor from moisture from the slab, provided you are careful not to puncture it. Sweep and vacuum the floor to remove all grit and dirt. If possible get a plastic sheet that will cover the entire floor without needing to join it. If this is not possible then make sure to overlap the sheets by about a metre and seal both edges of the joint with a moisture resistant adhesive tape. Once it's down lay your underlay on top as soon as possible and keep traffic to a minimum to avoid the danger of puncturing the membrane.

The meter you have will only give an indication of the moisture content very close to the surface of the concrete, to get the best result with the equipment you have, do the following: Get a 1 metre square piece of heavy plastic sheet and place it in the centre of the room, tape around the entire edges of the sheet with gaffer tape. By doing this the moisture in the slab under the sheet will come into equilibrium throughout the depth of the slab, i.e. the moisture content will be the same throughout the depth of the slab. After 3 days, peel back the sheet and take an indication with your meter of the moisture content in the centre of the square. This reading will now give you a better indication of the true moisture content in the slab. Hope this helps and let us know how you get on.

p.s. check with Brooks, but the question of "less than 5% moisture content" only comes into play if a damp proof membrane is not being used, using a DPM will provide the best insurance against problems with moisture effecting your flooring.