Roof Deck Pedestals

[Frank]

We are getting a number of requests to use plastic pedestals to hold up wood or concrete pavers for walkways over roofs in/on type 2 buildings.

Examples

http://www.bing.com/images/search?q=bison+paver+pedestals&id=8E5F83FB07FB669C6ABFEA1983A328BD37075B3E&FORM=IQFRBA#view=detail&id=8BE1136D2CA5A65EE7D4780E4E8801C6A59E2D2A&selectedIndex=10

http://www.bing.com/images/search?q=bison+paver+pedestals&id=8E5F83FB07FB669C6ABFEA1983A328BD37075B3E&FORM=IQFRBA#view=detail&id=F7F9CBC7A30A2A7DBB484A446A082231B88619DD&selectedIndex=33

The Ipe wood is suppossed to meet teh requirements for fire retardant wood but the polypropylene supports have only certification under UL94 HB which is a small scale screening test.

How are youall handling these

 

[steveray]

Neat product....I don't think it meets code though......

410.4 Platform construction. Permanent platforms shall be constructed of materials as required for the type of construction of the building in which the permanent platform is located. Permanent platforms are permitted to be constructed of fire-retardant-treated wood for Types I, II and IV construction where the platforms are not more than 30 inches (762 mm) above the main floor, and not more than one-third of the room floor area and not more than 3,000 square feet (279 m2) in area.

That is the only break that I know of for a combustible floor in a noncombustible building....You could probably approve it as an alternative if they can prove it is equal to FRT lumber....

 

[Paul Sweet]

I don't think 410.4 would apply to this, unless it were a raised area for performances, etc. Chapter 8 just applies to interior finishes, and I don't think there's anything in chapter 15 that addresses this.

The low shims have been used for quite a while, and I think they would be OK, but I'd be worried about potential flamespread with the high ones.

Concrete is probably heavy enough to stay in place, but uplift could be a problem with wood (although Ipe is denser than most woods).

 

[Big Mac]

Roof construction, including girders, trusses, framing and decking can be used in Type II construction. Section 603.1, item 1.3. If decking and supports are equal to fire-retardant wood or better, it shoud be acceptable.

 

[steveray]

Combustible floor construction not allowed in Type II construction unless you can make it work under 410 or whatever platforms is in your code.....Unless you want to go alternative means, methods, or materials in chapter 1...

 

[mtlogcabin]

Seismic loads might come into play for some

 

[north star]

= \ = \ = \ =

Dumb question, but how are these pedestals attached \ placed

on to the existing roof surfaces ?..........Also, after they are

installed, what happens if you need to periodically inspect

where the pedestal bears on to the roof surfaces [ i.e. - for

wear, ...any penetrations, etc. ]......Do they have an ES

rating or report ?

= / = / = / =

 

[Yikes]

Just ran across this old thread and thought I would add my comments. The plastic pedestals merely rest on top of the roof. They are not attached or permanently affixed to the building. They are held in place by gravity. Typically there will be perimeter parapets around a deck that provide lateral stability for the whole system; in other words, it is bound and enclosed on all sides, so there's no room to tip over.

Likewise, the paver stones rest atop the jacks. The pavers can be lifted off by anyone who has the muscle power to do it, so there's easy access for inspections or repairs. The small gaps between the pavers allow water to drain down to the roof below. The roof below needs to have its typical fire rating (e.g. class A in my area).

The pavers and plastic jacks are not considered a part of the roof, and they are outside the building envelope. On a practical basis, the pavers provide substantial protection from the sun, direct rain or hail, and from ashes from nearby fires. The roof below will not wear out.

This system is heavy, about 20 lbs per square foot dead weight.