Concrete Tile Roof

[newStruc]

I was figuring out the dead loads for a wood tower on a wood building. The wood tower has a concrete tile roof. I was planning to use 15 psf as weight of my tile. My co-worker is saying I am being too conservative. He says the weights vary from 9 to 12 psf. What is the general weight that I should assume for concrete tile?

Do towers have sprinkler systems, I would like to know if I need to add the sprinkler dead loads to the tower dead loads as I did for the main roof.

 

[swivel63]

how thick is it?

 

[newStruc]

Looking at the arch'l drawings it is about 4" thick

 

[msquared48]

That seems awfully thick, unless it is the spanish tile which is curved, but only about 1/2" thick. With the flat tile, you are looking at only 3/4" thick if my memory serves me right.

If it is a full 4" then you are looking at 40 to 50 psf, and that is ridiculous. Normally 15 to 20 psf depending on the material, the manufacturer, and the style.

Mike McCann
MMC Engineering

 

[swivel63]

4" thick and only 15 psf? you sure it's made of concrete?

 

[newStruc]

At another location, I have another tower with a clay tile roof. Would that be also the same weight as the concrete tile or would it be lesser?

 

[swivel63]

clay? i would think lesser.

 

[msquared48]

Best thing to do though is to get the exact material spec from the Architect, then call the manufacturer and get the actual per square weight, and divide that figure by the actual coverage area they get per square, normally 90 to 100 square feet.

When you are dealing with tile roofs, long term deflection can be a problem, reading every major beam in the roof if it is too great. Don't be afraid to be conservative with your dead loads. It may save you a lot of future headaches.

Mike McCann
MMC Engineering

 

[msquared48]

For Clay tile, the Western Woods Use Book, on page V-7, suggests 9 to 14 psf, and adding 10 psf if mortar is used.

For 2" Book Tile, they suggest 12 psf, and 3" 20 psf.

Other tile types I see in the list range from 10 to 19 psf.

Bottom line is you really need to know what you are dealing with here.

Mike McCann
MMC Engineering

 

[newStruc]

As per the arch'l drawings, there is a layer of felt underlayment. Does that replace mortar for the clay tiles ?

 

[JedClampett]

Take a look at a clay or concrete tile website, like Monier (

http://www.monierlifetile.com/index.html).

They have a lot of information including weights and details. It's much better to use their actual weights as they know exactly what the overlaps are for their tiles. Plus, they give you the whole system (plywood, felt, battens, etc.) so you can add them in to your dead load.
As an aside, I would verify the Architect's details with the manufacturer. The final word on installation is likely to be the manufacturer's.

 

[Ron]

Generally, concrete tile will be in the 10-12 psf range, depending on configuration. Most concrete tile is flat, so the 10 psf range is reasonable. The underlayment will be either a self-adhesive flashing material, a heavy felt underlayment, or granule surfaced "roll roofing". If self-adhesive or heavy felt, figure 30 to 40 lbs per square (1 square = 100 square feet)...if "roll roofing" figure about 90 lbs/square.

 

[Lutfi]

I agree with Ron.

Regards,
Lutfi

 

[kslee1000]

Not familar with this subject, just to make a little noise.

Mike & Ron's number are good (from experience speaking) for preliminary design. Could be used for final, if you wish to add a few pounds extra for uncertainties. But Jed has led in the right direction - manufacture. However, find at least 3 brand names, as each may differ in method of applications and material properties.

 

[newStruc]

The architect is not sure who the manufacturer is going to be. He says, he will know only after the project goes out for bid.

So should I be using 12 psf for the clay tile roof as well? Or should I use the 14 psf for the clay tile.

Another question, do small tower structures on wood roofs generally have sprinklers? Should I account for them in my total dead load?

I am assuming the following

Concrete/Clay Tile = 15 psf
Plywood Sheathing (1/2") = 2.0 psf
Framing = 2.5 psf
Insulation = 2.0 psf
Miscellaneous = 1.5 psf
Total = 23 psf

Am I missing something? There are no mechanical units on the tower roof.

 

[msquared48]

If you must approach the design this way, then, in the structural notes or on the plans, specifically state that the dead load of the roofing is limited to XX psf. Any more will require a redesign of the structure, to include lateral. That will get their attention, and extra services if they continue to take stupid pills here.

Mike McCann
MMC Engineering

 

[msquared48]

Is the building sprinklered? If so - add 2 psf.

Mike McCann
MMC Engineering

 

[kslee1000]

What is the tower for - water tower, lookout tower?

 

[newStruc]

The tower is just an architectural tower. There is no means of access to the tower, though it has two windows on the wall suuporting it. I guess it is required for some architectural purposes.

 

[kslee1000]

Sounds like a "Bell Tower" Well, if no access, who is able to set fire (from inside)?