Typical house construction - little clay bricks

deepee · Posted: Sat Sep 09, 2006 10:23 pm Post subject: Let your house breathe

One risk with heavy air-con use in the humid tropics is the formation of a "dew point" within linings,walls and cavities.
This can lead to fungal growth,decay of materials,corrosion of fastners and termite intrusion into often unseen or unaccesable areas.
What I'm suggesting is that if you build in the tropics, it may be prudent to consider this possibility and allow for adequate venting in suspect areas.
Common thermal foil insulation can aggrivate this problem.Be aware that breathable foils are now available.
Too many good homes are constructed into "sealed tombs" due to the use of non-breathable materials nowdays. Finishings such as paints being some of the worst offenders.Just check around,many substitute breathable products are simple and cheap e.g lime washes.

Jaime · Ace Joined: 14 Jan 2004 Posts: 1888 Location: Sh*t Creek

Presumably this is as a result of migration of warm moist air from outside to inside? Does the due point occur on the inside face of the wall linings as the moist outside air condenses upon reaching the cool, air conditioned internal air temperature? Couldn't this be rectified by the fairly simple solution of correctly installing a suitable vapour barrier to ensure that moist air never gets cold enough to condense?
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deepee · Posted: Fri Sep 22, 2006 8:50 pm Post subject:

Jaime,
the dew-point forms( unseen )on the outer face of the inner lining in a cavity wall situation ,thats why ventilation should be considered.

sargeant · Ace Joined: 19 Sep 2006 Posts: 1351 Location: Hua Hin

just a small point in hua hin the water table is very close to the surface and as i have never seen a damp proof course or membrane in all the time i have been here Cussing

this results in rising damp
question 1, does the room cool as the outside exterior walls get hot and the water evaporates ????( i am not sure but i think so)
question 2,does any one think the thais do it on purpose to cool the house
question 4, if you have rising damp i dont think it matters what you use you might as well make it out of water filled leftover plastic bags whichever way it goes
at least it might be a way to get rid of the litter
Idea

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sargeant · Ace Joined: 19 Sep 2006 Posts: 1351 Location: Hua Hin

jaime
i am disapointed i was hoping or some input
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Jaime · Ace Joined: 14 Jan 2004 Posts: 1888 Location: Sh*t Creek

I have been away for a few days but boody hell - I didn't realise I had been given a time limit in which to respond! Anyway, despite the fact that my instincts tell me that this is a wind up my answers are as follows:

1. There is such a thing as the evaporative cooling effect - it was employed to great effect by the mediaeval arabs, most notably in the palaces and gardens of the Moorish Caliphate of Cordoba and later Granada where pools and fountains cooled the air. However, I have absolutely no idea whether water evaporating from a damp wall would cool your house. Anecdotally, I suppose that damp houses generally feel cool.

2. I can't believe that the Thais employ this as a cooling strategy by deliberately making their houses damp. Maybe there is some historical precedent but I am not aware of it. Mareukathaiawan Palace just north of HH (a beautiful, tranquil place for a half day trip if anyone's interested) did have a small water filled trench constructed right around its perimeter but I understand that it was intended to prevent crawling insects from scaling the building rather than for any cooling effect. It was (is) also only a couple of inches wide.

3 & 4. There ain't no Q.3 and Q4 is a statement rather than a question but I think the simple addition of damp proof membranes and courses would generally be a good idea if building masonry structures just a foot or so from ground level. There - a business idea for someone!
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"The man who never made a mistake never did bugger all" - Old Welsh proverb

"Why limit yourself to the death of a crummy celery stalk when you can eat a giraffe?" - PWEETA

sargeant · Ace Joined: 19 Sep 2006 Posts: 1351 Location: Hua Hin

jaime
sorry but no time limit sorry if you felt so hope you had a good time away

no its not a wind up i have never seen a damp proof course or a membrane in the 9 years i have been living here and as i worked in the building game at the same time working for Brit airways (night shifts)
i take a keen interest in how they build things here and do all my own building work myself
i like their design the houes and bungalows are ascetically at least to me very good. There larger buildings are not so good
their building techniques however are horrifying
i dont think they deliberately build for rising damp but i have noticed on my ground floor the bottom 2 foot of my walls are noticably cooler than higher up the wall
you are right of course why they dont put a damp course and membrane is beyond me especially with such a high water table

as for the trench the palace half way between cha-am and hua hin has a trench and as you correctly say it is to stop crawly beasties
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