Hi there
the house we bought part of it is on clay with concrete piles, its been partially
laid with black polythene moisture barrier a half finished job , it has that silver old so called insulation under the floor, my question is the area that doesnt have the moisture barrier is alot firmer and dry, the area that has moisture barrier is damp and moist underneath ( dry on top of polythene, Im not sure whether to continue it , or pull it completely out and let dry out..
can I have some advice please ?? if you know abit about this in your experiences .. cheers :)

daz1968 - 2021-04-14 18:58:00

Cover all the dirt and seal. Old silver, push up and push in polyester blanket. It will become dryer and warmer. Utube what do do. People will waffle on about the silver, but work out the safety issues. Exterior remove build up of soil from base boards. There should be vents in the baseboard to keep air moving.

gabbysnana - 2021-04-14 20:24:00

gabby is on to it.

all the dirt under the house should have polythene moisture barrier on it.
i recommend punching drainage holes in it at the low points (in case of wind blown rain or pipe leaks). make sure you peg it down well.

the silver paper degrades and probably does nothing now. rip it out and put decent insulation in.

now the reason the clay is dry without the moisture barrier is that the water evaporates out into the air and that moisture is going up into your house. the barrier keeps the moisture in the ground and out of the air.
the air vents are meant to remove the moist air but in practice it does bugger all.

the condensation in my place dropped in half overnight after fitting the moisture barrier.

tweake - 2021-04-14 20:44:00

The silver insulation is probably aluminium foil which is not recommended these days as it is an electrocution risk. A number of people have died by touching the foil that has been stapled to wiring.
I suggest that you turn the power off before removing the foil completely.

trade4us2 - 2021-04-14 21:19:00

tweake wrote:

gabby is on to it.

all the dirt under the house should have polythene moisture barrier on it.
i recommend punching drainage holes in it at the low points (in case of wind blown rain or pipe leaks). make sure you peg it down well.

the silver paper degrades and probably does nothing now. rip it out and put decent insulation in.

now the reason the clay is dry without the moisture barrier is that the water evaporates out into the air and that moisture is going up into your house. the barrier keeps the moisture in the ground and out of the air.
the air vents are meant to remove the moist air but in practice it does bugger all.

the condensation in my place dropped in half overnight after fitting the moisture barrier.

thanks especially that point about why clay is dry , as moisture going into house , Ive looked into it more and branz quote no issue with slighly moist clay under polythene loosening or dropping piles as its just on surface not further down

daz1968 - 2021-04-14 21:32:00

We had to install the barrier cloth under our rental to meet the healthy homes standard. It was about $700 installed for the full house. Hopefully the tenant finds it cheaper to heat the house. We should find out this Winter....

oakcottage - 2021-04-14 22:59:00

Yeah it is real cheap to get a contractor to install it. You could do it yourself, but it might takes ages.

tygertung - 2021-04-15 08:06:00

daz1968 wrote:

Hi there
the house we bought part of it is on clay with concrete piles, its been partially
laid with black polythene moisture barrier a half finished job , it has that silver old so called insulation under the floor, my question is the area that doesnt have the moisture barrier is alot firmer and dry, the area that has moisture barrier is damp and moist underneath ( dry on top of polythene, Im not sure whether to continue it , or pull it completely out and let dry out..
can I have some advice please ?? if you know abit about this in your experiences .. cheers :)

Black polythene moisture barrier, really is a "no brainer" for stopping moisture getting in to the house.

Worse case example is older garages with concrete laid directly on the dirt.
Any box's placed on the concrete get damp & rot the bottoms off after a few months.

mrfxit - 2021-04-15 10:54:00

Polythene is a cheap and easy method to prevent rising damp, which is more of a problem than lack of underfloor insulation

catwoman1974 - 2021-04-17 08:42:00

catwoman1974 wrote:

Polythene is a cheap and easy method to prevent rising damp, which is more of a problem than lack of underfloor insulation

i quite agree.
the effects of underfloor moisture is highly underrated.
one of the worse things i see on new buildings is not installing the moisture barrier before putting the floor down.

tweake - 2021-04-18 11:41:00