Welcome to BigScreenBiz.com

Different climate conditions I would imagine call for different types of roofing. Living in the north east I am concerned with snow and ice during the winter months. Could you give me some pointers on the best type of roof constructions for this area.

Check with your local building inspector. If your area gets a fair amount of snow there will be regulations on what pitch and how much reinforcement your roof will need. I have always been partial to peaked roofs myself to avoid snow and ice buildup. Flat roofs on the commercial buildings that I know need to be shoveled several times per winter.

Poppajoe

Most commercial buildings are of a size that flat roofs are the only practical solution. There are two aspects to consider; structure and roofing materials.

Structural Design:
The structure must be designed and inspected by a registered structural engineer, who will insure that the design meets all the requirements of your local code.

Roofing Materials:
The roof must be adequately drained. This is usually done by clreating gently sloping sections which slope to roof drains. Often, tapered insulation is used to build up the surface to create adequate drainage. There are many roofing systems in common use. The decision should be made in consultation with your professional consultants.

If a roof is properly designed and constructed in accordance with your Building Code, and with good workmanship, it shouldn't ever be necessary to go up there to shovel the snow.

Mesber or Smith,

Why do most commercial buildings have flat roofs while most houses have pitched roofs?

I understand why you can have a flat roof in Phoenix, but why do most commercial buildings even in the snowy North have flat roofs?

By the way, we have one of those 1950s barrel shaped roofs with scuppers. The intersection of the roof to the wall is a weak spot and has leaked many times.

Why don’t commercial buildings have overhangs? We had a torrential rainstorm last night and we have 4 roof leaks mostly in ducts. The exterior block walls were soaking wet, one would think that overhangs would protect the building more.


[This message has been edited by Large (edited November 08, 2002).]

Our one screen is approx 10,000 sq. feet with a peaked roof that has been standing strong for over 61 1/2 years, 60 of them with 1/2 inch slate tiles adding to the load. If possible peaked roofs just seem to drain better to me. Especially if you are in an area with a lot fo snowfall.

I am not a fan of flat roofs because they almost always seem to be troublesome about leaks, but I thought commercial buildings were mostly all flat roofed because of the HVAC systems. Is there a way to design a peaked roof with several HVAC units over different theaters?

Flat roofs vs pitched roofs usually require quite different roofing materials. Even with the slate roof which is a roof which could possibly last 100 years, a pitched roof which has shingles has a minimum pitch for the shingles to work as designed. While the accepted minimum for pitch with
shingles is a roof that has a rise of 3" for a run of 12 inches. Run equals half of the span of the building. Ex. 100' wide building has a span of 50 feet. 3" to the foot has a rise above the top of the wall of 150 inches which equates to over 12' of height.
Great deal of additional material to build this roof. A flat roof is designed for both live and dead loads, snow being dead. The type of roofing could vary from a rubber or pvc membrane to coal tar pitch and 4ply of felt mopped each coat.
There is no reason for parapet walls to leak if proper counter flashing has been installed. Biggest problem is heat expands and contracts roofing and any penetration such as curbs or drains or pipes or parapet walls where the roofing is turned 90 degrees is an area where failure is usually found first. We have had good sucess with tapered insulation as mentioned with ballasted roof. Slag or washed stone is applied to roofs to actually hold down the roofing material. Flat roofs work, but require a bit of maintenance as nothing is forever. Treasure that slate roof, it is a lost art and even finding replacement shingles is almost as imposible as finding someone that knows how to replace them.
lance

[This message has been edited by LanceC (edited November 10, 2002).]

Well, I'm not in the snowiest part of Canada, but we are set for about 4 months of winter here, and virtually all large buildings are flat-roofed using tar and gravel. Heavy wet snow is the only really bad type, but buildings should be designed for it (Hartford Civic Centre being one that WASN'T). Most snow will be blown off or melt with the black colour of roofing. Other than that, lots of light dry snow greatly lowers heating bills acting as insulation.