CM 214 Chapter 5 Review

How much should the vapor retarder overlap at the seams?

An overlap of 3 inches to 4 inches is inadequate. An overlap of 6 inches to 12 inches is recommended.

When must you determine the location of the perimeter drain?

You should determine the location of the perimeter drain before excavating. You'll need to adjust the excavation area to accommodate the piping.

Why should all flatwork slope away from the home?

All flatwork should slope away from the home to ensure adequate lot drainage.

Why might a customer prefer a basement to a crawlspace?

A customer might prefer a basement to a crawlspace because a finished basement provides additional living space.

The soil at your site is expansive soil. You've just finished placing concrete for the stem walls. What might you have to do if the completed stem walls aren't centered on the footings?

After stem wall construction, it's too late to adjust the reinforcement. If the home is built on expansive soil, and the stem walls aren't centered on the footings, you might have to extend the footings to balance the force through the footings.

How should backfill be placed?

Backfilling at a 45-degree angle in small 2-foot to 3-foot lifts prevents damage to the wall.

Why should you conduct quality control inspections?

Conducting quality control inspections reduces construction costs, prevents construction delays, and reduces warranty callbacks.

Before any soil treatment for pest protection is applied, what should you do?

Confirm that the lot has passed all required utility inspections. If you have any plumbing or excavation work performed after the soil treatment has been applied, the soil treatment must be reapplied for the warranty to be valid.

Which of the following explains the purpose of corner pins?

Corner pins mark the corners of the foundation walls.

From a corner in the perimeter, you measured 6 feet down one side and made a mark, then measured 8 feet down the adjacent side and made a mark. If the corner is square, what's the distance between the two marks?

If the corner is square, the distance between the two marks completes a 6×8×10−foot triangle.

What might happen if the slab dries too quickly?

If the slab dries too quickly, it won't cure properly and reach its full compressive strength. Curing relies on hydration, the chemical reaction between the Portland cement and the water in the concrete. Water is needed for adequate hydration to occur.

Why is it important to confirm that all penetrations in the vapor retarder are completely sealed?

If the vapor retarder is working correctly, water vapor moving up from the soil will condense into liquid water on the underside of the vapor retarder, and eventually move back down into the soil. If there's a hole in the vapor retarder, this water will wick into the slab through capillary action, damaging flooring and promoting mold growth.

The surveyor is setting the corner pins for the footings of a stem wall at Lot 72. Which of the following should you confirm before the surveyor leaves?

Make sure the surveyor marks out the corners of the footings, not the corners of the walls that will rest on them.

A wire mesh has been laid out in preparation for a placing a basement slab. What should you confirm about the wire mesh?

You should confirm that the mesh is overlapped 6 inches and tied at the seams.

What is one method of bracing a foundation wall before backfilling?

Placing a layer of granular fill material provides foundation drainage, but it doesn't brace the foundation wall. You can brace the foundation wall by anchoring it to the first floor.

Why shouldn't you place pipes parallel in grade beam trenches?

Placing pipes parallel in grade beam trenches weakens the grade beams.

In residential construction, where are post tension slabs commonly built?

Post tension slabs are commonly built in areas with expansive soil.

Why are chairs used in footing construction?

Rebar is supported on chairs to ensure that it will be in the center of the footing after the concrete is placed.

What purpose does reinforcement serve?

Reinforcement gives concrete structures tensile strength.

What should you look for at lintel areas?

Reinforcement is particularly important around lintel areas. Make sure that rough window and door openings are reinforced per code. The typical requirement is that reinforcement be placed within 12 inches of the opening.

In what locations might the spacing requirements for anchor bolts be more stringent?

Spacing requirements for anchor bolts might be more stringent in high wind or seismic areas.

The foundation crew is ready to place concrete. At what elevation should the foundation be?

The actual elevation cannot be more than 1 inch higher, and cannot be any lower, than the proposed elevation.

When inspecting formwork for the footings, what is the building inspector's primary concern?

The building inspector confirms that the footings are structurally sound. Keep in mind that the building inspector's main concern is occupant safety. It's your responsibility to confirm that the footings are placed in the correct location, are the proper width and depth, and are level and square.

For what is the expansion joint used?

The expansion joint allows the basement slab to expand without causing structural damage. It also helps the foundation contractor to locate the basement floor.

Typically, how far above the grade line should the waterproofing application extend?

Typically, the waterproofing application should extend 4 inches above the grade line to provide adequate foundation protection.

For a monolithic slab foundation, why is it critical to set slab formwork at the correct elevation?

The formwork elevation drives the height of the slab, which is also the height of the finished floor of the home. If the forms aren't constructed accurately, the resulting inaccuracies in the foundation can create problems during the framing stage and utility installations.

What surfaces should be waterproofed?

The foundation wall, the exposed surfaces of the footings, and the brickledge, if applicable, should all receive the waterproofing application.

To what can you refer when checking the waterproofing application?

The geotechnical engineer's report will discuss soil conditions. You should refer to the specifications listed in the waterproofing subcontractor's scope of work when you check the application.

What is the recommended minimum grade drop in the first 10 feet from the foundation?

The grade should drop a minimum of 6 inches in the first 10 feet from the foundation.

The masonry subcontractor is on-site, building a block foundation wall. Where should he create a cove?

The masonry subcontractor should create a cove at the joint between the foundation walls and the footings to direct water away from the foundation. The area where the wall and footing intersect is vulnerable to water intrusion, and the coving directs water away from that area.

The masonry subcontractor is on-site, constructing a block foundation wall. Why should he or she know the locations of penetrating plumbing pipes and electrical lines, if possible?

The masonry subcontractor should know the locations of penetrating plumbing pipes and electrical lines, if possible, so he or she can install sleeves between the proper courses.

In post tension slab construction, what is one of the safety precautions you should take before applying tension to the strands?

The plumbing subcontractor isn't responsible for safety during post tensioning. You should get all nonessential personnel away from the area. Due to the high amount of tension applied to the strands, severe injury can occur if a strand snaps during the tensioning process.

What is the primary purpose of grading away from the foundation?

The primary purpose of grading away from the foundation is to drain water from the home.

Why should you slope the grade downward from the foundation?

The primary purpose of sloping the grade downward from the foundation is to drain water from the home.

You're conducting a slump test, and you've just removed the mold from the concrete. What is the slump?

The slump is the distance between the top of the mold and the top of the slumped concrete.

How out-of-plumb can the stem wall be?

The stem wall shouldn't vary in its distance from a plumb line more than ½ inch in any place.

In a post tension slab, how far below the surface should the slab strands be?

The strands should be at least 1½ inches clear of the surface.

You're building a stem wall slab. Who should you call in to mark the corners of the home on the footings?

The surveyor marks the corners of the home, usually with nails on the footings.

How deep should control joints be cut or placed into the slab?

The typical recommendation is that control joints be ¼ the thickness of the slab.

What does the vapor retarder prevent?

The vapor retarder prevents condensed water vapor wicking into the slab.

Typically, how out-of-plumb can a foundation wall be?

The wall shouldn't vary in its distance from a plumb line by more than ½ inch in any place.

You're checking the rebar for the footings or grade beams. What should you confirm?

You should confirm that all rebar is lapped and tied, is the correct size and type, and is supported off the ground.

A block stem wall is under construction. What should you check at the block cores?

You should confirm that the block cores are filled at the required intervals.

Before concrete is placed for the footings, at what locations should you be particularly aware of whether reinforcement has been placed?

Wire mesh overlaps don't affect footing and grade beam reinforcement. Footings and grade beams should be reinforced where they cross utility lines, because the soil is disturbed in those areas.

Why should you brace forms before placing concrete in them?

Without bracing, the forms could move or buckle when the concrete is poured.

Why do you need the plot plan?

You need the plot plan to check lot setbacks.

Why should you place filter fabric around the perimeter drain?

You place filter fabric to keep out silt and clay that can clog the perimeter drain.

Why should you keep wood forms moist in hot weather?

You should keep the wood forms moist in hot weather so they won't absorb the water from the curing concrete. If the wood forms are dry, they'll absorb water from the concrete, interfering with curing.

What should you do to test the drains?

You should pressure-test supply pipes. To test drains, pour water down them and confirm that they drain.

Under what conditions should concrete mix for a slab be air entrained?

You shouldn't place concrete if the temperature is consistently below 30 degrees. You should have the concrete mix for a slab air entrained when the concrete will be subject to freezing and thawing during and for the first few hours after construction.