TEMPORARY ROOF DECK WATERPROOFING

[gotlboys]

A friend is going to build the ground floor of this two-storey residential bldg and the second storey will be left for several months before continuation. The second storey concrete slab will temporarily serve as roof deck for certain period.
How do we prevent rain water from seeping into the temporary roof deck and reaching the ceiling?

Thanks so much.

-R

 

[bimr]

Suggest you build a roof over it as concrete is not waterproof.

 

[gerhardl]

Hi gotlboys,

Size? Climatic conditions?(frost, ice, snow, windforce?)

As bimr :Construct a roof. Suggestion: plastic tarpaulin, self-draining mounted, tight stretched, secured against wind, over steel or timber construction for instance of rented steel-scaffold parts.

 

[gotlboys]

Thanks so much Bimr and Gerhardl.

It is 8.5m x 13m residential bldg. I am in South East Asia, a tropical country; no snow and ice. Some suggested making the temporary RC slab slant of 3% and provide downspout to drain the rainwater. I don't know if it works well as what you suggest.

 

[bimr]

A RC slab is not waterproof, even with a 3% pitch.

You should install plastic sheeting such as a UV resistant HDPE over the concrete.

 

[cvg]

a properly designed and constructed concrete slab could be nearly water tight and with adequate drainage, it would reduce the seepage down to a very low rate. the top surface could be waterproofed with a membrane / coating which would greatly improve things. If not, then humidity in the bottom level will be high. when you finish the building you will want to level the floor which will take time and money to complete. you might want more than 3% slope to prevent any low spots that might not completely drain off.

 

[gerhardl]

I still think an external, temporary wooden or steel frame with a tightly stretched plastic (reinforced) sheeting and a fall of say 15 deg. both sides from top along midroof would be best. Let original roof surface be as is, but in addition protect either with impregnation (water-glass, water resistant/repellent but not 100%,) or other layers simple to build onto later.

The best solution is not the cheapest now, but the safest and one not likely to cost you repairs or additional maintenance later.