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Thread ID: 139523	2015-05-17 03:35:00	underfloor insulation	tweak'e (69)	PC World Chat

Post ID	Timestamp	Content	User
1400825	2015-05-17 06:10:00	Polythene sweats so any gap, tear or join in the polythene allows the moisture back into the above polythene area thus creating the evaporating situation you are trying to avoid. If it isn't damp under there now or after rain don't bother. As an ex builder who has worked on 3 different continents over the years I have seen so many problems crated when people mix polythene with buildings especially wooden ones. The only safe place for polythene in a building is under concrete.	gary67 (56)
1400826	2015-05-17 06:14:00	Polythene sweats so any gap, tear or join in the polythene allows the moisture back into the above polythene area thus creating the evaporating situation you are trying to avoid. If it isn't damp under there now or after rain don't bother. As an ex builder who has worked on 3 different continents over the years I have seen so many problems crated when people mix polythene with buildings especially wooden ones. The only safe place for polythene in a building is under concrete. Gary, a subfloor has to be ventilated and keep plants away from the subfloor vents so air can circulate. This paragraph here below is an approx. extract from a NZ standard relating specificly to the subfloor ventilation: To prevent subfloor dampness, provide subfloor ventilation openings over the whole subfloor area.Ventilation openings shall be not less than 3500 mm2 per m2 of floor area and evenly distributed around the foundation perimeter.	notechyet (4479)
1400827	2015-05-17 06:17:00	what is the unusual construction in your house? It's tr-iboard so no framing and no gib just solid walls. Also the floor is tri-board and has no joists, just steel beams at 1250(ish) spacings. Most products are built to wedge between joists at 400-600 type spacings. It's thicker than normal particle board floors though by quite a bit.	dugimodo (138)
1400828	2015-05-17 06:23:00	It's tr-iboard so no framing and no gib just solid walls. Also the floor is tri-board and has no joists, just steel beams at 1250(ish) spacings. Most products are built to wedge between joists at 400-600 type spacings. It's thicker than normal particle board floors though by quite a bit. You might need to fix/attach the insulation to the triboard if you can't fix anything to the steel.	notechyet (4479)
1400829	2015-05-17 06:26:00	Polythene sweats so any gap, tear or join in the polythene allows the moisture back into the above polythene area thus creating the evaporating situation you are trying to avoid. If it isn't damp under there now or after rain don't bother. As an ex builder who has worked on 3 different continents over the years I have seen so many problems crated when people mix polythene with buildings especially wooden ones. The only safe place for polythene in a building is under concrete. its always going to be wet under the polythene, thats kinda the whole point. no different to being under concrete. small holes etc in would allow standing water in, which is why it needs adequate drainage, which it has otherwise it wouldn't be dry now. i don't think small holes will do much. the amount of evaporating through such a small area is absolutely nothing to what it has now. concrete allows moisture through, so it really makes no difference if there is concrete or not.	tweak'e (69)
1400830	2015-05-17 06:29:00	It's tr-iboard so no framing and no gib just solid walls. Also the floor is tri-board and has no joists, just steel beams at 1250(ish) spacings. Most products are built to wedge between joists at 400-600 type spacings. It's thicker than normal particle board floors though by quite a bit. i don't see any issue with that. just tack it to the floor. probably wrap around the beams as well.	tweak'e (69)
1400831	2015-05-17 06:35:00	found some old testing by branz. dirt under a dry house in auckland evaporates about 300ml per square meter per day. 200 square meter house = 60 liters of water per day.	tweak'e (69)
1400832	2015-05-17 07:42:00	Polythene sweats so any gap, tear or join in the polythene allows the moisture back into the above polythene area thus creating the evaporating situation you are trying to avoid. If it isn't damp under there now or after rain don't bother. As an ex builder who has worked on 3 different continents over the years I have seen so many problems crated when people mix polythene with buildings especially wooden ones. The only safe place for polythene in a building is under concrete.thats why I was advised against it, was surprised because these companies like to up sell	plod (107)
1400833	2015-05-17 08:04:00	found some old testing by branz. dirt under a dry house in auckland evaporates about 300ml per square meter per day. 200 square meter house = 60 liters of water per day. With poor or no subfloor ventilation you can guess where some of it goes and the consequences. Ground cover weighed down suppresses the rising of the moisture + the ventilation trying to take any away.	notechyet (4479)
1400834	2015-05-17 08:14:00	With poor or no subfloor ventilation you can guess where some of it goes and the consequences. Ground cover weighed down suppresses the rising of the moisture + the ventilation trying to take any away. explain please. do you mean that the ground cover interfering with ventilation under the floor ? or the ventilation will take away any remaining moisture?	tweak'e (69)
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