Structure Inspection Section#2 Floors Quiz#5

You should have finished Study Session 4 and Quick Quiz 4 before starting this Study Session.

The estimated completion time is one hour.

Objectives
At the end of this study session, you should be able to:

• Describe subflooring materials and their function in one sentence each.
• List nine subflooring problems.
• Describe in one sentence each pre-stressed and post tensioned concrete floors.
• List seven concrete floor problems.

Briefly describe post-tensioned concrete flooring.

Post-tensioned concrete has steel cables in a sheathing, typically. The concrete is poured around the cables when they are relaxed, and as the concrete cures, the cables are pulled tight, from one end while the other end is anchored. The tension in the cables puts the concrete under compression.

Briefly describe pre-stressed concrete flooring.

Prestressed concrete floors use steel cables under tension put in place before the concrete is poured. The concrete is poured around the cables and then the cables are let go.

How can you tell if the slabs have had their support undermined?

Tap on the slab and listen for a hollow sound.

In what part of the building is rusting steel reinforcing bar in concrete slabs likely to be a problem?

Suspended garage floor slabs

List five reasons concrete slabs may settle or heave.

1. Footing or foundation settlement 
2. Soil compaction or erosion below slab 
3. Excess concentrated loads on the slab 
4. Footing or foundation heaving due to frost, expansive soils or tree roots 
5. Soil heaving due to frost or expansive soils

List nine common subflooring problems

1. Rot and insect damage 
2. Sagging or springy subflooring 
3. Damaged or cut 
4. Cantilevered or unsupported ends 
5. Prior repairs 
6. Concentrated loads 
7. Squeaks 
8. Swollen waferboard 
9. Cracking ceramic tiles

List seven common concrete floor problems.

1. Cracked 
2. Settled 
3. Heaved 
4. Hollow below slab 
5. Scaling or dusting 
6. Spalling 
7. Rusting reinforcing bar

Name three common subfloor materials.

Planking, plywood, waferboard

Subflooring below ceramic tiles should be stiffened to prevent tile cracking. Name three ways that this can be done.

1. setting the tiles in at least 1-1/4 inches of concrete

2. using thicker or double subflooring (total thickness of roughly 1-1/4 inches)

3. using blocking to support the subflooring between the joists

What is one possible disadvantage of diagonal plank subflooring?

Unsupported edges may be springy

Subfloors act like - (two answers)

joists

beams

Shrinkage crack patterns in concrete floors are usually -

Random

All concrete floors in houses are suspended slabs.

False

Plywood should be installed with its long dimension parallel to joists.

False