Help with my bid documents

weedyacresAugust 12, 2014

We're doing a room addition onto our small house. I figured out the layout (thanks for the input from here!), and had a draftsperson make formal drawings. We're going to hire out the concrete work and the framing shell, and we'll DIY install siding and finish out the interior.

My question is what do I need to include in bid documents to make sure I've got the proper things specified. The only other time I've bid something out, I had a much more comprehensive set of plans, so the plans were sufficient to solicit bids.

My goal is to have it complete enough that subs can bid accurately and that there will be no question about design and materials.

Here are the drawings I've got:

Some of the details on my list:
Footings to code requirements
Crawlspace floor: 2â thick concrete. Roughly even with existing grade.
Floor joists 2x10, 16â OC, parallel to existing house.
Plywood t&g subfloor, even with existing kitchen subfloor, glued and screwed
Wall framing 2x4, 16â OC
Ceiling height 8âÂÂ-6âÂÂ
Exterior sheathing of ???
Windows and doors supplied by owner
Windows properly flashed to sheathing, room wrapped in Tyvek
Roof stick-framed with ?? Hardware, 8/12 pitch (field verify)
Roof sheathing of ???
Roofing: underlayment of ??, will specify shingles

I'd appreciate input on items above: what do I specify for the ?? items, what should I change, what have I omitted?

Also, I'm debating whether to buy the building materials ourselves or have them do it and then double check them.

Thanks for any and all input.

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live_wire_oak

The bidders will need to know your window schedule to ensure that they will use the right flashing materials for the window type. And you'll need to know what the right flashing materials are as well, as you're the GC.

Sheathing and decking should be OSB, preferably with exterior foam cladding for the walls, which impact your siding application methodology. For roof underlayment, I prefer a synthetic roofing underlayment rather than felt paper, but some prefer old fashioned felt. 30 rather than 15 pound is a nominal increase in $ for a product with a bit more body and water resistance.

Your roof framing as well as wall framing should be called out in the framing diagrams prepared by your draftsperson, following the prescriptive tables, and will depend on the snow load you see.

    Bookmark   August 12, 2014 at 4:18PM
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kirkhall

Crawlspace access is where (make sure you know if you'll put it in your addition floor somewhere, or if you'll require concrete foundation cutting from your existing crawl into the new crawl).

Can you take this to your local permit office to ask what they'll need for the permit? In my area, they required and reviewed the framing details. Once I had that, it made it easy for the framers to follow. I'd think you could do the same--find out what they need for permit, make sure you have that, then take it for bidding.

And, you'll do insulation yourself? Make sure they frame with enough room in the attic space to get the needed amount of insulation (thickness) up there.

    Bookmark   August 12, 2014 at 4:32PM
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weedyacres

Thanks, guys.

I asked the draftsperson if this was enough info for the framers and they said yes. Grr. I mean, the walls are pretty no-brainer, but I figured surely we needed something for the rafter design. I'll go back to them on that. Permit requirements in this town don't require engineering details, just a plot map to ensure compliance with setbacks, and 2 inspections.

I'll add the window schedule. They're just basic vinyl ones. We just used that Grace stick-on stuff on the 2 other ones we replaced...did we do right?

Do we need to specify thickness/grade of OSB, or is there just one standard sheathing type?

What synthetic underlayment do you recommend for the roof? We're in the lower midwest, so we get cold winters and hot, humid summers.

Crawlspace access will be via an existing basement window. I'll add that to the bullet list.

    Bookmark   August 12, 2014 at 7:55PM
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renovator8

If you draw a section through the house you will be able to note almost everything and avoid a written specification the builders are likely to ignore. Make it large enough to easily read.

It would show and note the framing heights, framing member sizes, anchors, tie downs, rafter clips, typ. header, insulation, weather barrier/vapor retarder/drainage plane, attic access, roofing, gutters, attic ventilation, ext. cladding, interior finishes & trim, crawlspace & ventilation, slab, vapor retarder and crushed stone under slab, foundation materials and depth and drainage.

Framing plans would probably not be necessary.

I would use 1/2" Huber Zip wall sheathing to eliminate housewrap or if you want to fuss with that stuff use Tyvek or Typar (no substitutions). 5/8" OSB or plywood roof sheathing, Ice & Water Shield full coverage (there would only be a small portion not covered after using it on the eaves, valleys and ridge).

The window flashing would be a butyl based flexible tape (Tyvek Grace, etc. - I don't like to use asphalt based flashing on plastic although it seems to be done routinely.

The windows seem small. I would at least lower the sills a foot. This would be a major improvement for a reasonable cost.

    Bookmark   August 13, 2014 at 7:09AM
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