The one challenge with flat roofing is ensuring proper drainage.
Flat roof roof drainage plan.
Green roof solutions gr32 and gr52 drainage panels come in 24 x 24 interlocking squares constructed of 100 recycled high density polypropylene hdpp.
Most draining systems on flat roofs have a poor design or are not correctly installed.
Each of these systems has its own pros and cons.
Or 12 drains required.
Select number of roof drains and calculate the roof area sloped to each drain.
50 000 4 400 11 36.
According to bs 6229 bs 8217 flat roofs should be designed with minimum falls of 1 40 to ensure a finished fall of 1 80 can be achieved allowing for any inaccuracies in the construction.
It is very critical to position drains for maximum effect.
Poor drainage can lead to serious issues with flat roofing from leaks to structural damage.
The grs gr52 panel size is 24 x 24 x 2 125.
Often the flat roof has a slight pitch in the rafters.
There are roof coating products available if there isn t enough slant or slope to accomplish this.
As water flows to the edge a metal diverter is usually placed at the eave to prevent dripping at walkways.
Determine 100 year 1 hour rainfall rate used for location of building.
So often we find that inner drains are high on the roof causing water to pool around them.
Size horizontal storm drainage piping.
A major maintenance issue shared between all types of roof drains is debris removal.
Unlike other roofing types that are slanted or sloped to allow water to drain automatically flat roofs need a built in drainage system to help remove moisture and debris.
Take the roof s total square footage and divide by the total square footage handled by one drain.
It is a requirement of building regulation part h that adequate provision is made for rainwater to be carried from the roof of the building.
Ipc provides four steps to size the roof drains on a building.
There are three types of drain systems commonly used on flat roofs.
A pitch of 1 4 per foot 2 percent slope is often used to help prevent wa ter from ponding on the roof.
On flat or low slope roofs that drain to one end lower right in the sketch especially if the building rear wall does not include a projecting eave or soffit a clogged gutter or downspout send water down the building rear wall flooding the structure through its wall or through windows.
A flat roof will often have a parapet or false wall sur.
The result is the number of drains needed.
There are three types of drain systems on a flat roof.
Using tools from the international plumbing code ipc it s not that hard.
Your building and location can help determine which drain will fit your roof needs.
Sented on the roof plan.
