View Full Version : Do I need a damp proof course for laundry timber frame?
6th Feb 2011, 07:12 PM
I am in the process of building in my outside laundry. It is undercover on a big patio slab at the back of my house. Basically I just want to build a L shaped timber frame to enclose it, then render this and paint to match house.
Do I need to put some type of flashing or damp proof course down? Its on a complete flat slab that doesnt really see any water. Would it be ok just to use a waterproof silicone around the base and sides of the timberframe, then blueboard and render of it?
6th Feb 2011, 10:21 PM
Just waterproof the room as it were an internal room. Waterproof the wall to floor interface.
I have seen timber rot because it placed inside plastic, all it did was hold the water and cause rot rather than prevent it.
When waterproofing I cut through the plastic.
6th Feb 2011, 10:49 PM
How would i go about waterproofing it like an internal room? Weatherproof insulation sheeting over the timber frame and silicone around the base and corners of the frame? I have a roll of sheet flashing, would it be worth using that?
7th Feb 2011, 02:04 AM
The standard internal waterproofing consists of a waterproof membrane, 1/ apply waterproofing product, 2/ apply membrane,3/ apply another coat of waterproofing product, ensure no pinholes.
7th Feb 2011, 10:24 AM
Hi Mate. Before erecting the timber frame you need to consider if the concrete slab your sitting the frame on has a damp proof inserted beneath the slab. ie was the slab laid on a plastic sheeting, If you don't know assume the slab was not, and insert one line of viscourse under the bottom plate to protect the timber from rising damp that can come up through the concrete. You do need to use a sarking under the blueboard, so make sure the bottom plate sits on the edge of the slab (even let the timber overhang the edge by 5 >10mm) so that you can run the blueboard at least 25mm down past the the underside of the timber. This will create a drip groove so water running down the wall does not get drawn up under the bottom plate. I gree with previous advice, waterproof the interior of the room like you would for a bathroom. PS don't forget to allow for controll joints in the blueboard and you need double studs where ever a contoll joint occurs.
7th Feb 2011, 11:19 PM
thanks for the info guys.
The slab has a damproof course as i have cut through some of it before and have seen the plastic. The slab doesnt have an edge where the frame is going for the laundry, its a 10x7m pebblecrete outdoor area underneath a large shed covering.
Its basically going against the rendered block wall which makes an L and the L is the timber frame if you know what i mean. I was just going to villaboard around the wet areas of the laundry but gyprock the internal L of the timber frame part. The only time this thing can get wet is if I am hosing out the back, other then that water cannot get to it by rain etc.
So is there any type of flashing I need to put under the frame and a guide to doing it? I have some metal film flashing and have seen it being used on frames on outer edges of slabs but this frame no near anyedges or direct rain.
8th Feb 2011, 12:29 AM
Two things come to mind.
1/ Under the building code the laundry is a wet area and should be sheeted with a water resistant sheeting and waterproofed to the standards.
2/ Ask any insurance company what is the most common room to suffer flood damage, the answer will be the laundry.
I realise the water may well drain out and into an area off the end of the slab and do damage, but if your non water resistant sheets get wet it could well be another problem you don't need.
Some insurance companies have realised that asking for a copy of your waterproofing certificate is saving them millions of dollars.:)(
8th Feb 2011, 06:33 PM
So would it be ok to just silicone around the outside of the frame or do i need something underneath the base timber? I will waterproof it internally but the outside is just going to be blueboard and render.....so just wondering if there is something to go under the base like flashing. Any one have a diagram that would help heaps
9th Feb 2011, 10:16 AM
I would place a a run of viscourse under the bottom plate, turn it up on the inside 30 or 40mm on the inside before you fix the enternal lining and turn the viscourse down on the outside so you can run the blueboard past the bottom of the bottom plate, 10 or 20mm will be fine. If you want to run a bead of silicone, thats fine, any thing you can do now to prevent moisture is time well spent.
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