Framing Residential Construction Mr. Todzia
Types of materials used in Res. Con. • Conventional framing- dimensional wood lumber • Douglas Fir • Spruce • Both are softwoods (usually trees with needles and cones) • Easy to work with- cuts and nails easily • Grow very quickly, so extremely renewable. • Structurally very strong
Types of materials used in Res. Con • Pressure Treated lumber • For exterior use or when touching steel or concrete • Usually Southern Yellow Pine trees • First the wood is thickly coated with preservative chemicals and then placed into a sealed chamber where it is exposed to extremely high pressures. This pushes the chemicals from the wood's surface deep down into the interior making the wood entirely treated throughout. • PT is often heavier • It usually has a greener tint in color for easy identification
Types of materials used in Res. Con • Engineered wood • Two types • Oriented Strand Board OSB • Laminate Stand Lumber, or Laminate Veneer Lumber • OSB is a Panel, similar in size shape and look as a sheet of plywood. • LSL/LVL is a structural lumber substitute. • Stronger than conventional lumber • Can span greater distances • Very expensive
Types of materials used in Res. Con • Plywood- 4 x 8 ft panels made from thin layers of wood glued in opposing grain directions. • Used most often as sheathing and decking. • Very strong because of the opposing grains. • Comes in sizes from ¼ inch to ¾ inch thickness
Attaching to foundation • Houses are anchored to their foundations by Anchor bolts which are put into the top of the foundation as the concrete is drying. • A pressure treated sill plate is then bolted on these anchor bolts. • Everything else is then attached by nails, screws or bolts to these sill plates. • To keep water, bugs and moisture out, Sill Seal is used as a barrier between the top of foundation and the pressure treated sill plate
Floor Structure • The floor structure is built on top of the Sill plate. • First the Rim/Box Joist is put on edge on top of the sill plate. • Floor joists are then run from one side to the other to create the floor system • Often there is a main Carrying beam that runs from one side of the foundation to the other to support the floor joist in the center of the building.
Floor Structure • Floor joist can be made out a few different materials: • Conventional Lumber • I-Joist • Microlams
Floor structure • Openings in the floor system could be for stairs or openings to other floors • They are created by “heading off” the floor joist and transferring the load to another member. • Bridging- is used to stiffen the floor joist and keep them from racking. • Decking is glued and laid on top of the floor joist to create the subfloor • Decking materials include tongue and groove plywood or OSB.
Wall Construction • Material- Usually conventional lumber like Douglas fir. Some exceptions include • Heavy timber- post and beam • Log construction- log cabin • Masonry
Wall Construction • Components • Bottom plate • Top plate (and second Top plate) • Studs • King, Jack (trimmer), cripples • Header • Window sill • Corners (interior and exterior) • Partitions
Openings in walls • Openings in framing for windows and doors are called Rough Openings. • They are called rough because they are slightly bigger than the window/door so the window or door can fit in without trouble. • Another thing to remember is that when building a wood framed house all the framing from the floor joist to the rafters should stack on top of each other to most efficiently transfer the load of the building to the ground.
Next floor • If there is a second or third floor on the house, then the second floor deck is constructed in the very same way as the first, except it is built on top of the first floor walls instead of the top of the foundation and sill plate.
Stairs • Stairs can be some of the most difficult things to build in a house. Stairs are supported by long boards stretching from one level to the next called stringers. • Treads and risers are then laid on top of stringers. These can be done simply with 2x 10’s if they will be covered with carpet,, or need to be done with hard wood if the wood will be exposed. • Usually a specialized stair professional is hired to do the stair work.
Ceiling joist • Ceilings are usually just the bottom of the floor joist from the floor above. • The ceiling on the top floor may have to be added and is usually just a dimensional board called a ceiling joist that carry’s the load of the drywall and any possible attic loads.
Roof Structure • Roofs are typically constructed in 2 ways: • Rafters or premade Trusses • Rafters are roof framing components that are cut and installed individually • Trusses are premade offsite by a truss company, deliver and put in place by the contractor.
Rafters • Depending on the length and span, rafters are made out of 2 x8, 2 x 10, or 2 x 12 dimensional lumber. • They are cut to the appropriate angle on each end and a cut called a “birds mouth” is cut to fit on top of the upper most wall. • The advantage is that you get a nice attic space • The disadvantage is that they are very time and labor consuming, which means they are expensive.
Trusses • Trusses are ordered to size, pre-manufactured offsite and trucked in. • The are usually made out of 2 x 4’s and intersections of components are covered with a metal splice. • The major advantage is that they are light-weight and easy to install. • The disadvantage is that you don’t get an attic space with trusses
Roof Sheathing • Roof sheathing is typically ½ in. plywood. • It is installed directly over the rafters or trusses and nailed in place. • Depending on the spacing of the trusses or rafters, code may require small metal clips called plywood clips to be installed between sheet of plywood in each rafter bay.
House wrap • The last step to complete the framing is to protect it from the elements before the contractor can get to the siding. • This is done with a moisture barrier called house wrap. • There are lots of different types and companies that make house wrap products. • The most common name is Tyvek. • It’s main purpose is to protect the wood during construction and to allow moisture out of the building, and prevent it from going in.