Window Stools

Specification & Product Discussions MasterFormat 2004 Discussions
1

Miami-Dade County school system has various stool materials at its windows, usually in walls finished in gypsum board - sometimes just finished in bare concrete or block.

No one material is overwhelmingly favored in today’s designs, but natural stone, acrylic and polyester countertop materials, and precast terrazzo are commonly used, along with occasional epoxy- or polyester-bound composition material. Available lengths of 4 to 8 ft are desirable - but even then some tile is used.

Wood is frowned upon here, and marble is avoided for school work, even though the latter is a pretty good buy and is readily available.

Currently there is no mention of window stools in the school system’s master guide, but contractors have been donating them for years.

Rather than add them in the 09 20 00 Plaster and Gypsum Board area, a fresh location as 09 78 00 Window Stools seems a good move - covering a range of suitable products, spelling out their installation (a thin but strong cementitious or organic cement supporting at least 50% of the stool breadth, when properly detailed), and suitable to plaster-, gypsum board-finished - or unfinished - walls.

I certainly don’t want to encourage one-page sections in Divs 03, 04, 05, 06, and several in 09, to cover every likely stool material. A single function-based section instead of a slew of material-based ones is in order.

The term “stool” is properly used to distinguish from “sill” - which is good for describing what goes on the outside. I read a recent drawing note: “interior sill” - which could have been avoided with a more specific term.

“Sill” is also used to describe the bottom member of a window frame. AWI Figures 300-05 and 1000-02 note the interior trim as “stool”, reserving “sill” for the bottom of the window frame.

“Stools” is a worthy addition to lists of standing wood trim, as in AWI Quality standards.

Where I grew up and first worked on houses, “stool” was the common term, although nobody made an issue if a greenhorn said “sill”. Here in Miami I can get a quizzical look, depending on what part of the world you come from.

What think you?

2

Chances are there is a lot of heresy in this, but haven’t really evaluted the situation [and we do a lot industrial work with unsophisticated finishes] but we have the following in 061000 Rough Carpentry–

A. Interior window stools: 3/4" particle board covered with plastic laminate. Units to include integral apron drop, as per details.

Maybe not th best of examples but we get good results with this and for our purposes. Have used other materials for projects with higher finishes-- Corian, etc.

3

Two possibilities:

09 31 08 - Thin-Set Window Stools

The base number 09 31 00 includes a wide variety of materials - ceramic, plastic, metal, stone, etc. Adding the “08” Level 3 number could be a clue that it pertains to openings.

09 05 31 - Window Stools

The 09 05 XX being a Common Work Result for Division 09; The Level 3 “31” to tie it back to the thin-set installation method. You could also use a Level 3 “50” to tie it back to Division 08 windows (08 50 00).

4

We prefer solid surface material for a number of reasons. If there are countertops and other items of the same material, which is usually the case, 06-6116 - Solid Surfacing Fabrications is a reasonable place to specify window stools. I would not add a special section for minor items such as this.

5

Combs’ 09 31 xx suggestion makes sense, although I’d be inclined to give Thin-Set Window Stools an 83 suffix.

Since terrazzo will be my first local product preference, I hope that the next MF adds an 09 31 36 Thin-Set Terrazzo Tiling heading. We use a lot of terrazzo tile in the schools here.

For stools, we can specify that strips be sawed from 96 x 56 x 3/4 or 5/4 in. locally stocked terrazzo slabs and the exposed edges eased to a small radius.

The 09 31 xx section would include/permit everything currently under 09 31 00, plus countertop cast plastics, any mineral in a polyester or epoxy matrix, and cement terrazzo (no wood).

My gosh - maybe I had better stick with 09 78 00!

6

If you’re in the artificial materials world, 06-6100 would include not only SSM, but cultured marble, quartz surfacing, and similar products. If a given project had window stools of several types, I would consider a special 09-xxxx section, but even then, I probably would put them in the same sections used to specify other materials of the same type, i.e., plam with woodwork, SSM with countertops, tile with tile.

7

If I understand work results correctly, which I don’t, I would also side with a Division 06 section. since the carpenters will generally be installing these items as part of millwork and trim work.

8

Mr. Chambers’ idea makes the most sense to me. Getting the stool in place would be part of the trim and millwork “Work.” That section could certainly reference other sections for specific information about stone or man-made products. I’m for keeping it simple.

9

Where is the official list of trades and subcontracts published so that we can use it as a guide for establishing resposibilities for “work results”? Is there a one-size-fits-all national standard? If the standard exists, does it describe regional considerations and historical precedents that affect assignments of responsibility.

I get confused when trying to address trade and subcontract jurisdictions in work results, such who installs doors and door hardware, who provides firestopping at pipe and duct penetrations (each subcontractor or a single specialty contractor), and who is responsible for material characteristics of cast-in-place concrete for various items such as bases for lighting standards, housekeeping pads in mechanical equipment rooms, headwalls for storm drain outfalls and planter walls.

Perhaps my sense of inadequacy to define these stems from not having a contractor’s license or a degree in construction management. That is, I’m not qualified to do the jobs of the general contractor and construction manager. I’m also not willing to do their jobs without additional compensation and relief from liability.

10

By the way, shouldn’t the work result that started this discussion be “window stooling”.

11

Gotta watch out for loose stools…

12

I think this thread has started to have some misconceptions about work results in relation to trades and subcontracts.

This is the definition of work results from the ISO standard:
“Construction result achieved in the production stage or by subsequent alteration, maintenance, or demolition processes and identified by one or more of the following: the particular skill or trade involved; the construction resources used; the part of the construction entity which results; the temporary work or other preparatory or completion work which results.” Skill or trade is only one of the elements involved.

The principle that specifications are not written to define subcontracts (except in special cases such as mulitple contract projects) remains intact and is not changed by the fact the MasterFormat is organized by work results. A particular work result may be contracted in any way the prime contractor wants under AIA A201. A particular work result may by performed by various trades in various parts of the country dependent upon local rules or tradition.