April 1998 Table of Contents

Commonsense Safety: Lessons Learned

Accidents happen, even on OSHA-approved job sites. When it comes to day-to-day operations, these stories from working contractors show that sound judgment and common sense are the keys to working safely. Read more

Cordless Finish Nailers

Six months after Paslode released a new Impulse trim nailer, Porter-Cable introduced a hoseless finish nailer of its own — the Bammer. JLC’s tool expert looks at how design differences affect performance, maintenance, and usability. Read more

Framing Rake Walls Framing Rake Walls

You don’t have to be a math genius to figure the angles on gable end studs. A Colorado builder explains his simple system for laying out and cutting rake walls. Read more

Frequently Asked Framing Questions

Do you have to double 2x12 trimmer rafters when installing a skylight? Can you remove collar ties in an attic? Just how strong is a toe-nail? We asked four engineers to answer these and other structural questions. Read more

Mortar Bed Shower Floors Mortar Bed Shower Floors

Curbed tile shower pans have to be watertight. A veteran tile contractor shows how careful detailing of a waterproof membrane and special drain makes for a trouble-free shower floor. Read more

Case Study Rain Screen Siding Retrofit

Moisture trapped behind wood siding can cause the finish to fail and the siding itself to cup and buckle. In extreme cases, the sheathing and structure below may deteriorate. Leaving an air space behind the siding is the best way to prevent these problems. Read more


Fiber-cement corners, undercabinet lights, brick veneer details, competitive bidding Read more


Urban building boom under way, sick building study, EIFS manufacturer not liable for failures Read more

Fiber vs. Wire Mesh Reinforcing Q&A Fiber vs. Wire Mesh Reinforcing

Q: Which is better at preventing cracks in concrete slabs: fiber reinforcement or wire mesh? Read more

Q&A: Pressure-Washing Before Painting

Q: Is it a good idea to pressure-wash wood siding before painting? It seems like this would drive a lot of water into and behind the siding — water that might still be present when the paint is applied. And what about pressure-washing decks? Read more

Nailing Patterns for Built-Up Beams Q&A Nailing Patterns for Built-Up Beams

Q: What’s the best nailing pattern for built-up beams? Read more

Horizontal vs. Vertical Sheathing Q&A Horizontal vs. Vertical Sheathing

Is plywood sheathing installed horizontally (perpendicular to the direction of the studs or rafters), with joints staggered, stronger than panels that are installed vertically? Read more

Q&A Deflection of Plywood vs. OSB

Q: Does OSB sag more than plywood when installed horizontally over 24-inch-center rafters? Read more

Why Add Plywood to a Door or Window Header? Q&A Why Add Plywood to a Door or Window Header?

A plywood layer in a typical built-up header adds marginally to its strength, but there's a more important reason it might be necessary. Read more

Doubling Rafters at Skylight Openings Q&A Doubling Rafters at Skylight Openings

When removing one rafter to install a skylight, is it necessary to double the two rafters at the sides of the opening and the headers? Read more

Q&A: Purpose of T&G Plywood Q&A: Purpose of T&G Plywood

Q: Does tongue-and-groove plywood add extra strength or stiffness to a floor system, or does it just help prevent floor squeaks? Read more

Locating the Splices in a Built-Up Beam Locating the Splices in a Built-Up Beam

An engineer explains why it is best to set all of the splices in multiple span built-up beams directly over the posts. Read more

Q&A: Strength of PT Lumber

Q: Does CCA pressure treatment adversely affect the strength or durability of framing lumber? Read more

Q&A: Weight of Steel vs. Lumber Beams

Q: For the same loads, which is heavier, structural steel beams or lumber beams? Read more

Rafter Thrust in a Shed Roof Rafter Thrust in a Shed Roof

Does a shed roof addition need collar ties to restrain the outward thrust of the rafters? Read more

Q&A: Shear Strength of Gypboard

Q: I’ve heard that engineers give no structural "credit" to gypboard, but I know it greatly stiffens partitions when I nail it up. How much shear strength does drywall really have, and why not credit it in the design? Read more

Q&A: When Are Collar Ties Needed? Q&A: When Are Collar Ties Needed?

Q: Collar ties don’t seem necessary in attics where the rafters come all the way down to the ceiling joists. Can you remove some of them to create headroom? Read more

Calculating Loads on Sloped Roofs Q&A Calculating Loads on Sloped Roofs

Should live and dead roof loads be calculated based on the horizontal run of the roof, or on the actual length of the rafter? Read more

Q&A: Safety Factor in Wood Construction

Q: Doesn’t the safety factor in wood construction mean that most wood structures are way overbuilt? Read more

Q&A: Unventilated Crawlspaces

Q: Since 1983, we have been using unvented crawlspaces under many of our energy-efficient housing projects. Our county has recently hired a new building inspector who is unfamiliar with this building practice and can find no provisions for it in the BOCA code. He would like us to provide evidence that unvented crawlspaces are sound building practice in our climate. We build in a 9,500-degree-day climate. Our crawlspace construction includes 2 inches (R=10) of rigid foam insulation on the outside of the foundation from footing to subfloor, a continuous 6-mil poly ground cover sealed at the joints and the outside wall, and R-19 batts in the floor joists. We have inspected most of these systems over the years and have found no evidence of wood rot or crawlspace moisture problems. What is the latest building science information on unvented crawlspaces, and how is it integrated into building code? Read more

Q&A: Using Purlins & Struts To Reduce Rafter Spans Q&A: Using Purlins & Struts To Reduce Rafter Spans

Q: Does using purlins and struts at midspan allow you to cut the roof span in half compared with what’s given in a rafter table? Read more

By Design Making a Flat Roof Work

Designing a flat-roofed addition Read more

Computer Solutions: WinEst Pro Plus 4.0

Estimating with WinEst Pro 4.0 Read more

Kitchen & Bath

Adjustable floor outlet, T-Square cutting guide for drywall, prefab molded eaves, permit protector pouch Read more

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