Browse Forums DIY, Home Maintenance & Repair 1 Apr 26, 2011 9:20 am Hi, I have a bit of a moisture problem under our timber floor. I have seen some products that are solar powered fans to increase the airflow through the underfloor area. Has anyone used one of these devices (eg. Envirofan)? I was thinking of making one myself from bits sourced from Jaycar, using the existing brick vents as the outlets. Re: Underfloor ventilation 4Jul 19, 2011 12:59 pm I had a similar problem and I was advised by a couple of damp experts not to install fans as it may dry out the subfloor too much (can cause structural problems) and to try larger vents first. Obviously all houses are different so hope you don't have any issues. Need help with travel insurance? Visit my site: Travel Insurance Reviews Re: Underfloor ventilation 5Feb 16, 2012 10:36 pm jymmit I am about to install two 120mm 12v computer fans to vents to help dry out my underfloor area. Will have them on a timer so that they only run during the day. Will let you know how it goes Hey Jymmit, how did you go with the fans ? did they do the trick ? We have an issue with damp soil under the house, and it’s starting to smell in the living room, and bedroom. I just got one online and will be installing it over the weekend. Cheers Shot81 Re: Underfloor ventilation 6May 21, 2012 1:23 pm Suppose as a ventilation engineer (amongst other things) and one who has had to retrofit an underfloor ventilation system under our extension I can add some advice 1. Exhaust fans are next to useless - better than nothing but certainly not worth the $$ I saw when first I researched the subject 2. What really gets rid of moisture are two things - air movement and (sorry to get technical) differential vapour pressure 3. Having lots of openings to outside will allow the differential vapour pressure to equalise the underfloor humidity to that ambient humidity .....this has its limits if it rains days on end 4. If you decide to use fans then ALWAYS use supply air fans and ducting - push the dry outside air inside the underfloor space and distribute it around the void via (flex) ducting system - I used an in-line bath room fan (200 dia) and some lengths of flex ducting with a few Y-pieces .... not too exxy Now the few times I recommended the supply air fan solution I was challenged as the industry appears to have standardised on exhaust fans - try this quick test. Light a birthday candle and place it about 1/2 metre away, now blow gently towards the candle. You should notice that without much effort the flame will flicker due to air movement. Now suck air like you have never done before ...... the flame will not be affected As some of the wiseheads say in my industry "you cannot suck out a birthday candle" Hope this addresses this common issue Re: Underfloor ventilation 8Dec 03, 2012 8:25 pm Everyone seems to be treating symptoms and not necessarily the illness. Yes ventilation is important and essential but what can cause excessive dampness is supply of water usually from poor drainage, leaks or other sources. Looking at ventilation in isolation from other building elements may not solve the problem. You are better of with a professional opinion Foremost Building Expert in Australia,assisting with building problems/disputes, building stage inspections,pre-contract review advice for peace of mind 200 blogs http://www.buildingexpert.net.au/blog Re: Underfloor ventilation 9Dec 07, 2012 1:17 pm I agree with BE. Get rid of the source of the problem ie water getting under your house somewhere and the problem will be solved. Having enough vents in your outside walls to ventilate the sub-floor is always a good idea anyway so you may also have to install a few others. It is also important to make sure that vents are put in opposing outside walls to get the cross flow effect. A surface or sub-surface drain around the perimeter of your house may redirect any water away from the problem area. Stewie 1 8701 Brass fly wire, you will need to cut it, shape it and jam it into brick slots 1 5494 |