We have a 5-story building over a basement (sloped site based on grade plane). The shoring wall establishing the basement level is a stand-alone design. The owner wants the entire structure to be constructed as wood-framed (costs / makes sense). Can this structure be entirely Type VA construction? Table 504.4 indicates "5" for a sprinklered building. What is confusing me is that since we are essentially building a 6th level (basement) out of wood-frame, would we need to change our Type of construction to IIIA (510.10)? Type IIIA comes with all sorts of restrictions as well (for our project mezzanines and a 12,000 gsf limitation for fire walls). Normally, we would just create a concrete podium (Type I) and build on top (Type V).....but having a stand alone shoring wall is offering us an opportunity to cut costs by creating a framed "podium"(?). Can we construct this building entirely as Type VA or do we still need to consider this a mixed construction type or Type III?
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Mixed construction type or not? / 5 over 1 (basement)
- Thread starter Brady7xq
- Start date
steveray
SAWHORSE
Depending on what code you are using look at IBC 510...
510.4 Parking beneath Group R. Where a maximum one
story above grade plane Group S-2 parking garage, enclosed
or open, or combination thereof, of Type I construction or
open of Type IV construction, with grade entrance, is provided
under a building of Group R, the number of stories to
be used in determining the minimum type of construction
shall be measured from the floor above such a parking area.
The floor assembly between the parking garage and the
Group R above shall comply with the type of construction
required for the parking garage and shall also provide a fireresistance
rating not less than the mixed occupancy separation
required in Section 508.4.
510.4 Parking beneath Group R. Where a maximum one
story above grade plane Group S-2 parking garage, enclosed
or open, or combination thereof, of Type I construction or
open of Type IV construction, with grade entrance, is provided
under a building of Group R, the number of stories to
be used in determining the minimum type of construction
shall be measured from the floor above such a parking area.
The floor assembly between the parking garage and the
Group R above shall comply with the type of construction
required for the parking garage and shall also provide a fireresistance
rating not less than the mixed occupancy separation
required in Section 508.4.
I need to clarify.....there is no parking in the project. All 6 levels (5 + 1) are R-2 occupancy.
Our jurisdiction (Seattle) allows for 5 stories in type VA construction (sprinklered). And I understand that the basement doesn't count against that. What I'm asking is if the basement can be of wood framed construction.
steveray
SAWHORSE
TABLE 504.4a, b
ALLOWABLE NUMBER OF STORIES ABOVE GRADE PLANE
The basement is allowed to be built out of whatever the building is allowed to be built out of.....*exclusions apply void where prohibited....
ALLOWABLE NUMBER OF STORIES ABOVE GRADE PLANE
The basement is allowed to be built out of whatever the building is allowed to be built out of.....*exclusions apply void where prohibited....
Paul Sweet
Sawhorse
IBC 1807.1.4 allows wood foundations:
"Permanent wood foundation systems shall be designed and installed in accordance with AWC PWF. Lumber and plywood shall be preservative treated in accordance with AWPA U1 (Commodity Specification A, Special Requirement 4.2) and shall be identified in accordance with Section 2303.1.9.1."
They were developed for single family homes & townhouses. I don't know whether they can be used for a 5 story building.
If I remember correctly the AWC only requires 6 mil polyethylene waterproofing. If I had to do a "permanent" wood foundation I would use real waterproofing such as Bituthene or similar rubberized asphalt sheet.
"Permanent wood foundation systems shall be designed and installed in accordance with AWC PWF. Lumber and plywood shall be preservative treated in accordance with AWPA U1 (Commodity Specification A, Special Requirement 4.2) and shall be identified in accordance with Section 2303.1.9.1."
They were developed for single family homes & townhouses. I don't know whether they can be used for a 5 story building.
If I remember correctly the AWC only requires 6 mil polyethylene waterproofing. If I had to do a "permanent" wood foundation I would use real waterproofing such as Bituthene or similar rubberized asphalt sheet.
I was trying to choose my words carefully, but perhaps not carefully enough. Maybe I should have said “even if the basement is Type VA construction.”
I’ve seen 6 stories of wood R-2 done before. One is the basement. The courtyard up one story.