Product Performance

Remedy For Bouncy Floor Trusses

Question: 

We are experiencing problems with bouncy wood floor trusses. I'm wondering what the industry standard is on deflections (live and total load). Also, do you have any ideas on how to decrease the deflection without affecting the profit margin significantly?

Roof Truss Plate Dislodgment

Question: 

I am investigating a roof failure in a 22-year-old structure. The connector plates have peeled open like a banana skin in several instances. The teeth do not appear sheared or torn at the wood surface. However, the plates will be in firm to one member and separated in the other (a gap of about 1/32 in.). Although there are large deformations, the roof is still standing. There was a heavy snow before the problem became apparent. Do you have any insights?

Floor Vibration

Question: 

We have designed a custom home that needs a good solid floor, with low vibration perceptibility. The system we have specified consists of 2 in. of gypcrete over 1 and 1/8 in. thick plywood or OSB. The floor trusses are 20 in. deep at 16 in. O.C., spanning 31 ft. 6 in. The preliminary truss design shows a double top and bottom chord with a total load deflection of 1.30 in. (l/290) and a live load deflection of 0.65 in. (l/581). The basement ceiling will be 1/2 in. gypboard nailed to the bottom of the trusses.

Duct And Light Penetrations Of Fire Rated Assemblies

Question: 

In a small scale multi-family residential project, I'd like to use a wood truss floor-ceiling assembly to achieve a one hour separation between units. I'd like to directly attach the drywall to the underside of the trusses & use the truss space for ducts & lighting (the floor above will be lightweight concrete on plywood sub-floor). UL assemblies do not seem to address the duct/light penetrations in such an assembly. Can I achieve a one-hour rating in such an assembly and how are penetrations addressed? Can the ducts in the truss space serve both units above and below?

Impact Sound Transmission Through Floor Assembly

Question: 

A condominium project I am involved with is experiencing a sound transfer problem through the floor/ceiling assembly between the first and second floor. You can hear every footstep, from an adult to a child. The floor assembly consists of a carpet and pad, 3/4 in. OSB sub-flooring, 15 in. deep wood trusses at 16 in. on center, 9 in. fiberglass batt insulation and a 5/8 in. gypsum board ceiling. The trusses span 20 ft. with air/heat ducts between the trusses. Will an additional layer of 5/8 in. gypsum board attached to 7/8 in.

Proper Bracing Of Valley Framing

Question: 

It is critical that permanent top chord bracing is supplied by proper nailing of the valley truss bottom chords to the carrying truss top chords, through purlins or properly installed rated roof sheathing. If the sheathing is not carried through under the valley framing, then the permanent top chord bracing must be supplied in another manner.

Fire Cuts

Question: 

What type of construction uses a fire cut truss? Could you describe a fire cut truss?

Truss Storage Responsibilities

Question: 

We have a customer that bought trusses in June. The trusses were shipped [ and one month later are] being set. The chords have weathered and bowed. What is the industry standard for dealing with this problem? What is our liability in this situation? We were not aware of any delays on the customer’s part and shipped as requested. Note: These trusses are 62 ft. scissor trusses.

Repairs To Field Modified Damaged Trusses

Question: 

As a home inspector, I have recently inspected an existing home with an attic truss system installed. Several of the truss web members have been cut away to allow access to an attic-mounted heating system. Can you recommend repairs to a truss with cut web members?

Truss Failure And Repair

Question: 

I am a professional engineer looking for information concerning the failure of metal plate connected wood trusses and methods of repair. I am looking for this information with regard to developing recommendations for the repair of truss systems in the floor structures of two-story multi-family dwellings. I see frequent failure of truss systems of this type in both in bending and due to catastrophic failure at the gussets.