Window openings in foundation wall

Window openings in a #foundation wall weaken the ability of the wall to resist inward #pressures. Any horizontal earth pressure on the portion of the wall beneath the #window must be resisted by the weight of the #wall, or be transferred to the #masonry or #concrete on either side of the #opening. As the width of an individual window increases, the masonry or concrete becomes less able to transfer these #loads, and a point is reached where the wall beneath the window may be pushed inward.

If windows are too close together, there is an insufficient amount of wall to withstand the load transferred from the wall beneath the window. This also must be controlled. Even if the openings are kept relatively small and reasonably spaced, however, as the percentage of wall openings increases, the overall strength of the wall decreases, and failure could occur.

When a foundation wall contains an opening greater than 1.2 m (4 ft.) in length, or contains openings whose combined total length exceeds 25% of the total wall length, then the portion of the wall beneath such openings is considered laterally #unsupported, and the wall around the opening must be reinforced to withstand the earth pressure. In addition, when the length of solid wall between openings is less than the average length of the openings it separates, the openings are considered as a single opening. These conditions are shown in Figure 9.15.-14.

Quoted from Illustrated Users' Guide - NBC2015

#foundationwall #earthpressure 

How are plans reviewed? -- #18

 How are plans reviewed? -- #18

How did you find a designer for your tenant space alteration? Had you been considering hiring a code expert to help you saving time and money?

I was a professional plans examiner in the City of Calgary. I reviewed and approved more than 8000 #projects in the past 12 years. I found one fact that more than 50% of the building permit #plans have to be on hold after the preliminary review. Some of them are on hold for more than one year to get approved. The main reason for this kind of delay is that the designers have difficulties to understand the building code requirements.

Unfortunately, as business or building #owners, they don't have any idea of which designer is the best for their job. Their might pick one from the yellow pages randomly or be attracted by one with fancy name or website. It is really hard to avoid a disastrous result.

Another fact I found is that up to 80% of projects, including interior renovations, #additions and new #buildings have the space to save at least 20% of the construction #cost. Thinking about an unnecessary fire separation, the cost can be saved is more than 50% of that wall.  If you can use #wood studs instead of #steel studs for your #partitions, you can save more than 40% of the studs cost.

One example I have reviewed recently is a six storey new building. It was designed as a #noncombustible building. I found if we could make the grade 600mm higher, the whole building can be built as #combustible building. The cost saving is more than a million.

One of the extreme projects I found is a primary #school building. The Building area is more than 3000sqm. The cost of the building is more than 30 million. It should be built as noncombustible building as per the building code, but it is actually built with combustible materials. What a danger to the school kids and what a waste of the money!

I hope this question is helpful when you plan to hire a designer for your next project. No matter which designer you are going to hire, it will be beneficial to have a Building Code expert to back you up.  At least, we might know if you have to avoid that designer for your project. 😁

#plansexaminer #buildingpermit #preliminaryreview #buildingcode #fireseparation #primaryschool #Buildingarea

9.15.4.3. Foundation Walls Considered to be Laterally Supported at the Top

 9.15.4.3. Foundation Walls Considered to be Laterally Supported at the Top

Exterior foundation walls are considered #laterally supported at the top if: 

  • they support solid #masonry construction, 

  • #joists are embedded in the top of the #foundation wall, or 

  • a #floor system is anchored to the top of the foundation wall. 

These conditions are illustrated in Figure 9.15.-13.

Quoted from Illustrated Users' Guide - NBC2015

#foundationwall 

Footing Thickness

 9.15.3.8. Footing Thickness

When a #footing supports a foundation, the soil exerts a pressure beneath the footing. Where a footing is wider than the foundation wall (or column) it supports, the portion that projects beyond the wall (or column base) is bent upward. If unreinforced, such footings tend to fail along #shear lines that extend downward at an angle of about 45º from the face of the wall. To be within this shear line, therefore, the footing projection is limited to the footing #thickness, unless the footing projection is reinforced. 

If the supported loads require very wide footings, their thickness may become excessive. The cost of additional #excavation and #concrete may justify the use of reinforcing or other appropriate measures to reduce the thickness of the footing.

The concrete footing thickness, T, must be at least equal to the footing #projection, P (unless the footing is reinforced), and be not less than 100 mm (4 in.) (Figure 9.15.-8). Note that as special soil conditions or footing loads increase, so must footing thickness. 

Quoted from Illustrated Users' Guide - NBC2015

#footingthickness

Flat ICF walls

 Flat ICF walls

Foundation walls made of flat #ICF units need to be not less than the greater of 140 mm (5 1/2 in.) or the thickness of the wall above. Flat ICF walls need to be laterally supported at their tops and bottoms.

Quoted from Illustrated Users' Guide - NBC2015

#foundationwall #ICF

9.15.4. Foundation Walls

 9.15.4. Foundation Walls

Foundation walls are intended to support the loads transferred to them from the building #superstructure, and to safely resist any lateral soil and water pressures acting against them (Figure 9.15.-10). Where #hydrostatic pressure is present, the #foundation wall must be designed according to NBC Part 4.

Reasonably thick #cast-in-place concrete, #masonry foundation walls, and flat #ICF foundation walls are able to withstand the vertical loads from the superstructure of most Part 9 buildings with strength to spare. Both concrete and masonry, however, are relatively weak in tension. They are therefore reinforced with steel if the tensile forces become too great. Since foundation walls for residential and other small buildings are most often unreinforced, the most critical loads they are subjected to are the horizontal loads due to earth pressure.

If #basement walls are supported at the top, tension stresses are created as the walls deflect inward. If the walls are #unsupported at the top, they act as retaining walls, stabilized by the weight of the wall and the vertical superstructure loads. The greater the depth of #backfill, the stronger the foundation wall must be to resist the horizontal forces.

Quoted from Illustrated Users' Guide - NBC2015

#earthpressure #retainingwall #castinplaceconcrete #foundationwalls

9.15.3.4. Basic Footing Widths and Areas

 9.15.3.4. Basic Footing Widths and Areas 

This Article lists the minimum #footings #widths and areas based on anticipated loads. The footing sizes in NBC Table 9.15.3.4. are based on typical construction consisting of a roof, not more than three storeys, and centre bearing walls or beams. For this reason, NBC Clause 9.15.3.3.(1)(b) stipulates a maximum supported #joist span of 4.9 m (16 ft.).

The prescriptive requirements for #house footings are based on the limitations and assumptions depicted in Figure 9.15.-4, and are intended to deal with the majority of situations encountered.

Quoted from Illustrated User's Guide - NBC2015

#footingwidth

9.10.13.13. Fire Dampers

 9.10.13.13. Fire Dampers

This Article provides requirements for devices that enable #ducts penetrating a fire separation to be closed in the event of fire, so as to prevent fire spread across a fire separation. In most cases, a duct that penetrates an #assembly required to be a fire separation with a fire-resistance rating needs to be equipped with a fire damper.

Where a duct passes completely through a rated fire separation, it provides a potential #passageway for fire and hot gases. To maintain the integrity of the separation, a fire damper is usually required in the plane of the separation. This device is also required to have a fire-protection rating. It is normally held in the open position by a #fusible link, and is installed so that it will stay in place if the duct collapses (Figure 9.10.-19). The fusible link and damper must be accessible for #testing and #inspection.

#firedamper #fireseparation #fireprotectionrating #fusiblelink

Structural Considerations

 Structural Considerations

Foundations carry their own weight and the #loads transferred to them from the #superstructures they support to the ground. Vertical loads include the weight of the superstructure itself (dead load) and that of its occupants and contents (live load) in combination with the roof snow load. #Wind and #earthquake loads must also be resisted by the #foundation.

Where foundations extend into the ground and enclose space such as #basements and crawl spaces, they must also adequately resist lateral #soil and #water pressures acting against them. Foundations should not #settle significantly or unevenly over time. They should remain unaffected by the #freezing and #thawing of soils, and #moisture expansion and contraction in the soil.

Quoted from Illustrated Users' Guide - NBC2015

#deadload, #liveload, #snowload, #windload, #earthquakeload, #crawlspace

Common strategies used to direct water away from building foundations

 Common strategies used to direct water away from building foundations

#Rainwater and #snow-melt that do not drain away from a #foundation and into a #drainage system will seep into the soil next to the foundation. If the water cannot percolate downward quickly through the soil to a level below the footings, the soil can become saturated and can even create #hydrostatic pressure against the foundation and beneath the floor. This can cause leakage into the #basement or crawl space.

#crawlspace

Quoted from Illustrated Users' Guide -- NBC2015