We own a trulli which is currently used as a

10/15/2009 - 05:10

We own a trulli which is currently used as a holiday home.  It has been totally renovated and to protect it from damp we have where possible dug insulation trenches around the outer walls as well as put in french drains. All floors have been relaid and insulated but it is built on bedrock and there is of course no damp proof course in the walls, so there is an acceptance that it will always have a degree of damp.  Add to this that the rennovation was only completed this year so there is still several tons of plaster and cement to dry out.

I have been given several estimates on how long it will take for the new building work to dry out but two good summers seems about the norm.

Now to lessen the effect of damp on the inside, do we leave a couple of dehumidifiers on inside whilst it is shut up during winter or would we be better off leaving all the small windows open as this will allo a flow of air through the property?  My concern with the dehumidifiers is that it could dry thing out a bit too much and bring salts in the plaster/cement to the surface and even cause cracking.  We have where possible packed everything away in vaccusacks.

Any ideas, opinions would be much appreciated.



i think that whatever you do will be a bit 'pot luck'In my view - the best thing is to get as much natural ventilation as you can, and if you can safely leave windows open it will be better - dehumidifiers could, as you say, be a bit too fierce.

ahem... sorry about that.  I think leaving a powered dehumidifier on for ages will leave you stunned by a large bill so the windows option is probably the one. The howling gales blowing through will help move the damp off the walls that the dehumidifier won't reach and you will probably get less mould over the winter doing this. A friend of mine was asked by the builders to turn on the underfloor heating to dry out a house.... 3 days and €800 later they thought that opening the windows might have been a better idea. From fairly recent experience of drying out intonacco etc I'd say that you'll have forgotten about the damp issue by next spring. Our house was like a sauna for a few weeks especially on hot days but it was just mildly interesting rather than a problem. If you have solar heating you might as well dump to radiators throughout the winter for say an hour a day... it will help a tiny bit.

I don't have any experience in drying out a renovated house, but we do have a dehumidifier which we've learned to use all winter if we want to keep the mildew at bay without frequently opening windows and letting a lot of expensively heated air out of the house. If I had a place that was damp and going to be unoccupied for weeks on end, I'd be very concerned about what state the place would be in on our return.The dehumidifer we have is one of the little portable ones you see in appliance shops and DIY places. It's very effective and it has a control which you can adjust to set the desired degree of dryness. That, I'd imagine, should solve the problem of things drying out too fast.As far as the cost of running the dehumidifer is concerned, it's rated at only 235 Watts, so even if it ran constantly all day long, the power consumption over a week would be around 40 kilowatts. Whether the price of that much electricity is "too much" is a personal decision, but I'd be surprised if it's anywhere near as much as you use when you're living in the house.Al

We own a house that is built into a cliff face and has running water on the ground, cantina, floor in wet weather.  This used to create a lot of damp on the upper, living, floors, particularly as the house is left locked up from September until April.  We tried ventilation, but this did not help.  We have, for fifteen years or so, left two de-humidifiers running on low settings, so that most of the time they are not operating and burning electricity . This has been effective and not particularly expensive.

The best way to keep a house clean and mold free is without doubt controlling the humidity and the temperature of the house. After Maryland water damage fixed the humidity problems inside my house I was sorry I waited so long to call for help. Water damage and mold are a serious matter specially when you have toddlers in the house.

Agree to as many windows open as possible altho' mozzy nets over them will prevent ingress of bugs. Beware of anything being close to the walls , eg pictures, wardrobes, curtains , hangings as where there is stagnant air there you will get condensation and damage to walls and fittings Hope problem sorts itself out eventually.

Can anyone recommend any particular brand of dehumidifier? And how large/powerful should it be for a 55 sq metre flat with a very high ceiling? I can't even find an entry for 'dehumidifier' in the dictionary- what is it in Italian?  Any replies will be much appreciated!

We have a no-brand dehumidifier made in China (of course) which has worked well for about three years now. You can pay more to get a machine with one of the big air conditioning brand names on the front, but it's likely that the functional bits were also made in a Chinese factory. These things are not highly complicated devices; essentially, they're little refrigerators with a ventilation fan and a bucket to collect condensation. The only thing that will be worth investigating if you plan on leaving the machine running in a locked-up house is if the one you're thinking of buying has a way of by-passing the internal bucket. On ours, moving a little rubber plug from one point to another blocks off the drain to the bucket and allows you to connect a 10mm diameter hose which can then be placed somewhere that the condensed water can drain away (sink, shower, etc). Obviously, leaving a dehumidifier running in a house that has been locked up for the season will be of little use if it switches itself off as soon as the internal bucket is full. As for power rating, I'm certain that the cheaper units would be enough to cope with a 55 sq metre flat if you're thinking of leaving it running when no one is living there. On the other hand, even the most powerful one you can buy would have difficulties keeping the humidity down if all the windows in the flat are kept shut at all times and it's occupied by four people who each take two showers a day and eat porridge for breakfast, pasta for lunch and rice for dinner. In short, how well a dehumidifer works will depend on how much moisture is in the air as well as how powerful the machine is, so it's difficult to say how well one of the little units would work in your flat when it's occupied. One thing that's certain is that it would reduce the humidity to some extent. Al

In reply to by Allan Mason

Thank you, Al, that's really helpful. I had no idea what a dehumidifier actually was or how it worked until you told me!. Thanks also for the advice on by-passing the internal bucket- obviously one that you can attach a hose to would be better for us as the house would be shut up for several weeks at a time.

You may have to put away all your soft furnishings and bedding when you are away - we came back after 3 months to find everything mouldy but that was after we had removed a ton of cement from the stone kitchen walls and let them dry out.And had all the windows double glazed! I am very interested in the us of lime and earth plasters and what I have read points to a natural clay plaster actually taking in moisture.You can buy these plasters online now and they are no more difficult for a good plasterer to use than cement plaster.I know it wont solve your problem as you have already had the trulli plastered but it may be something others could consider?

Clay plasters will absorb internal moisture. If the problem is damp permeating externally then similar to pretty much all plasters (cement, gypsum etc.) cracking and failure are likely to develop. In older houses one of the biggest areas of damp penetration is through the floor. In houses with traditional terra cotta tiling you can see this by the white calcium deposits present on the tiles. Dehumidifiers can really help by absorbing and transfering moisture back outside but the real crux is to make the external structure (including floors) completely watertight. May not be an easy task though....

Thanks for that Capo Boi. I have just started the process of buying a small cottage that has been empty and run downish for a while. The floor is terracotta tiling and it is an upside down house, so bedroom on groundfloor.  scuse my ignorance but I don't know about these things so will probs have lots of condensation and leaky floor. You are right that penetrating water needs to be sorted. But how do folk sort stone floors? Sounds like a massive expensive job. But one that will probably have to be done. cheers

Hello moruzzo, If your floors are terra cotta check for white calcium deposits as I said above. Also check for very thin layers (almost like a really thin skimming stone) coming away. If neither are present then there is a good chance that your floor is watertight. Fingers crossed. After that its up to you whether you have them cleaned and sealed and by what method. If there is a problem, however, after making your floor good ( liner, screed, cement, I'm afraid), I would seriously consider replacing your cotta tiles with ceramic or internally sealed cotta tile substitutes. In my opinion maintaining hand made terra cotta tiles is a real nightmare. (I have lots and wish I did'nt). If you want a really good finish (one that does'nt mark when you drop a cup of coffee or drip olive oil) then you have to go down the professional cleaning route. Its simply not possible to achieve a longlasting sealed finish by hand applied products whether this is linseed oil, rose oil or something different. Unfortunately you need to use applications administered by machine. Its up to you what finish you are happy with but professional cleaning, sealing and polishing will set you back something around €20m2. and will need to be repeated every four to five years. Good luck on your new adventure and I hope everything works out for you.

Thanks Capo Boi. Before liner, screed, cement, if there is penetrating water or burst underground old pipes or something, how would I detect this. Would I need to get one of those professional type gadgets that you see on building progs. They are like ex-rays and also deep torch thingy. If it is not condensation etc then best to get rid once and for all. What would you reccommend in terms of investigation?