Pulse
17th February 2006, 09:29 AM
I have just finished throwing things around after my deck's WPM failed. I did it all according to the rules and was hoping for some advice as to why it failed and how to fix it.
Position: 4m elevated deck, northern side, partly over laundry
Framing: 190x45 TP joist hangers blocking at sheet ends 400mm spacing
15mm per m sloped from the dwelling.
Deck: 15mm hardie compressed sheet 5mm spaces, hardie jointing compound under screws (batten screws countersunk). 10mm polyethelene backing rod, hardies joint sealant. No leaks even prior to WPM.
WPM: Fuller WPM 300 primer 50% thinned, three top coats 20% thinned, 50mm bondbreaker tape, 100mm reinforcing tape, two layers reinforcing tape over some joins, most only one. ( I did thin the wpm slightly because it was toothpaste consistency and impossible to roll on)
was waterproof for 6 months until I tiled it!!
Tiled with 300mm tiles and davco ultraflex on the diagonal (no cuts for movement joints - longest dimension 6m) Only the centre done, no edging or grout yet.
It down the other day and about 3 major leaks developed. All at joints between the sheets. Against the house was OK. The membrane had 2-3 months sun exposure prior to tiling.
Why did it leak?
was it perished from the sun?
was it thinned too much (can recommends 2 coats only, unthinned)
was it too much too expect on a northern side with 43ºC days.
did the lack of expansion joints cause it (no grout yet though)
How to fix it?
If I pull up the tiles over the cracks will I be able to effectively reseal the membrane where it butts against the other tiles. (laid diagonal)
Should I just pull off all 30m2 and get pros to WP? What do they do differently?
I've heard of a thick clear membrane that can be applied over the top.
Should I put up a large waterproof shade sail? or a roof?
Would grouting and clear coating with grout sealer help?(without grout the whole deck become a shallow swimming pool)
Anyway, thanks for any help.. the deck was the more ambitious of my projects so I'm pretty disappointed.
Cheers
Pulse
Position: 4m elevated deck, northern side, partly over laundry
Framing: 190x45 TP joist hangers blocking at sheet ends 400mm spacing
15mm per m sloped from the dwelling.
Deck: 15mm hardie compressed sheet 5mm spaces, hardie jointing compound under screws (batten screws countersunk). 10mm polyethelene backing rod, hardies joint sealant. No leaks even prior to WPM.
WPM: Fuller WPM 300 primer 50% thinned, three top coats 20% thinned, 50mm bondbreaker tape, 100mm reinforcing tape, two layers reinforcing tape over some joins, most only one. ( I did thin the wpm slightly because it was toothpaste consistency and impossible to roll on)
was waterproof for 6 months until I tiled it!!
Tiled with 300mm tiles and davco ultraflex on the diagonal (no cuts for movement joints - longest dimension 6m) Only the centre done, no edging or grout yet.
It down the other day and about 3 major leaks developed. All at joints between the sheets. Against the house was OK. The membrane had 2-3 months sun exposure prior to tiling.
Why did it leak?
was it perished from the sun?
was it thinned too much (can recommends 2 coats only, unthinned)
was it too much too expect on a northern side with 43ºC days.
did the lack of expansion joints cause it (no grout yet though)
How to fix it?
If I pull up the tiles over the cracks will I be able to effectively reseal the membrane where it butts against the other tiles. (laid diagonal)
Should I just pull off all 30m2 and get pros to WP? What do they do differently?
I've heard of a thick clear membrane that can be applied over the top.
Should I put up a large waterproof shade sail? or a roof?
Would grouting and clear coating with grout sealer help?(without grout the whole deck become a shallow swimming pool)
Anyway, thanks for any help.. the deck was the more ambitious of my projects so I'm pretty disappointed.
Cheers
Pulse