Browse Forums General Discussion 1 May 13, 2015 2:00 pm We live in a full brick house in Sydney. The sandstone under the house is quite close to the floor - at the low point, 300mm, up to about 1200mm. We find quite a bit of moisture has permeated the sub floor into the rooms above. When we did the renovation, the floors were in pretty bad condition. Did some minor rectivficationthen carpeted over. We also installed fans and ventilation girls on both sides of the house. I am thinking of replacing the floors in the bedrooms with red tongue, and putting black plastic on the ground under the house. Any thoughts whether this should control the moisture rising into he house? There is no real evidence of rising damp - just a small section in one bedroom, Re: Moisture under house 2May 13, 2015 3:25 pm Not the best solution. Friends of mine did this in their similarly built house in Mona Vale and while the plastic worked for a while it didn't in a heavy downpour or long term. The path around the back of the house had been poured at about the same as the floor level inside. Water would find its way through the junction of the path and the sandstone then seep under the house as well as from where the small retaining wall on the other side of the path was. We jackhammered up the concrete path and excavated another 300mm down then poured another path. In the process we replaced the retaining wall ( which was falling down ) and installed a decent ag drain around the back of the house and down the sides for a way. The sandstone too ( and the mortar ) unless it is the really hard stuff can act as a bit of a sponge to water. To really get rid of all the moisture that is finding its way under your house you need to investigate where it is coming from - site drainage is usually the main cause. Any rising damp too should be halted by unbroken or uncompromised DPCs below floor level. I bet the original in your house would have been either slate or a layer of lead. Have you had someone have a look at that ? Stewie Re: Moisture under house 3May 13, 2015 3:33 pm Thanks Stewie. We replaced all the down pipes and plumbing so there are no leaks under the house. Since the sand stone is so close to the surface, it seems to hold a fair amount of water - which does not necessarily correlate to rain fall. We installed ag line at the front of the house (top side) when we renovated. We also replaced the majority of the DPC with the renovation. I think the rising damp on the small section of the wall is due to the gyprock touching the floor (which is at times damp). Confident that the DPC is in tact. Did water run under your friends house when it rained? We don't seem have this problem. Thanks once again for your reply - interested to hear your thoughts Re: Moisture under house 4May 14, 2015 8:55 am Hard to tell without seeing your house but none of your house should be damp at all if all those things are in place. With my friends place their path was too high and the water would pool at the edge up against the house then find its way through cracks or joins in the sandstone blocks then run under the house. Doing what we did solved the problem. An outside path or natural ground should be lower than the dirt under your house which should be 300mm below your bearers or 400mm below your floor joists just so you can crawl under there ( just ) for service work, pest inspections etc. Any ag drain should be lower again than the outside levels by 150-200mm with decent falls to make sure any surface water from rain or natural seepage from adjoining properties can be directed away from your house as quickly as possible. Stewie these look like missing batts. Go up and take a look. But yeah moisure meter is a completely different tool 4 9461 Yeah my reasoning is just that those house posts are designed for vertical load not lateral. I just didnt want to risk interfering with the existing house… 4 11550 |