Tag Archives: rafter

Framing tips and techniques

Some degree of framing is required for every house

There are different methods of wood framing.  Balloon framing is rarely used today. We will not enter into detail, but the link is provided if you are interested. Post and beam construction is another alternative not often used in residential buildings. The method of choice for most residential projects today is platform framing.

Framing is a large subject and I will have to rely on links a great deal. I am including the best and easiest to understand that I could find. I may add more in the future if I accidently hit on good ones. Please Note: I do not link to commercial sites except in rare cases. The links provide valuable information or graphics. They are primarily to info sources or other blogs.

Doing your own framing is not terribly difficult, but if you do not have experience there are many places to go wrong. Consider hiring an experienced carpenter to help. This is particularily true if your house is complicated in any way.

a house in the framing stage
A house in the framing stagemugley / Foter.com / CC BY-SA

Wood is commonly used for framing material in residential construction.

Wood is easily cut and fastened with ordinary tools. Strong and somewhat flexible, a wood frame house stands up well to many of the forces that may act upon it. Wood’s strength is not compromised by heat or cold. Although flammable, proper construction limits the risk from fire. If wood sheathing is used in the form of plywood or OSB, it becomes an integral part of the frame by acting as bracing. Wood is available in different grades suitable for different puposes.

Steel is sometimes used in interior walls for studs, bracing or beams. It is not flammable except at extreme temperatures and high levels of oxygen. Steel beams are very strong, and are used where long spans are desirable. Steel reinforcement is often used to achieve greater wind or siesmic resistance. If angle bracing is necessary, steel is a good choice for ease and speed. Steel interior studs can make walls that are truer and easier to finish.

Using steel studs The Family Handyman

The strength of steel decreases rapidly when heat is applied. For this reason, it is not a good choice for bearing walls in a house, as a structure may collapse quickly in a fire. Steel is also an excellent conductor, and it can create an undesirable thermal bridge if used in outside walls.

Even if the exterior walls are of a material that does not require framing, the interior walls, roof and ceiling will still need a framing system. Most builders today will use roof trusses. These provide the framing for both the ceiling and roof. No interior bearing walls will be necessary unless the structure is unusually complicated. Trusses are usually manufactured in a factory setting, so there is no point in going into detail on their framing. Trusses will need lateral bracing near the bottom or ceiling chord.

For this article, we are dealing primarily with wood framing.

Other types of walls such as straw bale construction require some framing as well, but  I have no experience. I will try to provide a link or two though. Some other types that require little framing are concrete, concrete block, log, or SIP (Structural Insulated Panel) walls.

framing material
—Framing material—Foter.com / GNU Free Documentation License

soon to be framing material

It Starts With LogsSeanMack / Foter.com / CC BY-SA

Wood frame exterior walls in hot or cold regions are usually 2 x 6 construction to allow for more insulation. In moderate climates, 2 x 4 construction is adequate. 2 X 4 is used for interior walls, except where extra cavity space is needed for plumbing or ventilation. For metric conversions on nominal lumber sizes use this link.

Floor framing may be with dimension lumber, or with engineered members such as trusses.

Engineered wood floor joists can speed construction and allow for longer spans. They are economical in many situations, and can compare in final cost to conventional solid wood floor framing. Floor trusses can allow even longer clear spans. Floor trusses are constucted similarly to roof trusses. Steel cross members are sometimes used. Both are worth considering for uniformity and dimensional stability.

Floor joists need to be firmed up against twisting done by installing bridging or by furring strips attached to the underside. Bridging can be steel or wood cross braces, or they can be solid wood. The second joist from the end should be laddered with the end joist. Framing a floor.

Openings for stairs need a double joist on either side and double cross joists at either end. Double stair openings should have further support underneath.

Floor joists are usually sheathed with 3/4 inch tongue and groove plywood or OSB. (Oriented Strand Board). Gluing and nailing is my favorite attachment method. Use a bead of construction adhesive on each joist. Nail with an air nailer loaded with nails specifically designed for floors, or use spiral nails.

Most walls are built laying flat on the floor platform, then lifted into place. They consist of studs placed 16 inches apart with a plate on the bottom and top. 24 inch spacing may be used for stud but does not provide as much support for interior drywall. A second plate is usually added to the top after the wall is raised. This is so trusses do not need to be placed directly over a stud and to tie the walls together

If plywood or OSB is used for sheathing, no further bracing should be needed in the exterior walls. Temporary interior bracing will be needed until the roof trusses are secured and interior sheathing is complete. If foam board or gypsum board is used for exterior sheathing, steel or wood bracing will be needed. If boards are used for some reason, they should be applied on an 45 degree angle. It has been many years since I have seen that done, but occasionally some one may saw their own lumber, and may not want to use more modern materials.

Said the stud to the drywall “I shouldn’t be in here. I’m innocent. I was framed.” Said the drywall “Quit complaining, you were nailed fair and square.”

Openings for doors and windows need headers and special framing techniques Provisions needs to be made for corners, and where interior walls meet exteriors. These are easiest explained with diagrams. Follow the link for a good explanation. There is more than one acceptable method.

Always consider the crown on the dimension wood (studs, plates and joists) when framing. Face all the crowns up on floor joists. They will sag to near level. If a few are extra high, you may have to plane them a bit. It is easier to nail a wall frame together if you keep the crowns up as they are laying on the floor, they won’t be rocking on you. Keep your straightest studs for kitchens and bathrooms where you have to hang cabinets. If you have an obviously bent stud in an interior wall you may be able to straighten it by cutting a saw kerf partly through it and scabbing a scrap piece alongside. When nailing on a top plate, place the crown opposite to the one underneath. You should be able to pull them straight if you work from one end.

TJ harvesteri
Log harvester16valve / Foter.com / CC BY-SA

You can save time by checking crowns ahead of time and marking with a v. Fasten the 2 bys with 3.5 inch coated nails or 3.25 with an air nailer. Length of nails for sheathing will depend on the thickness. 2 to 2.5 inch should be good, and spiral or ring nails are a good idea for sheathing, especially for the roof. Check your local codes for sizes and minimum spacings. I always put in a few extra to make up for unnoticed misses. It is sometimes hard to tell if you have hit the stud when using a nailing gun.

Caulk along the bottom plate after standing the wall. It would be better to caulk underneath, but this could make things slippery and dangerous when you stand the wall.

You can add a lot of strength against uplift if your sheathing laps over the rim joists and the top plate. If you feel this is too difficult, then use steel ties to hold things together. In some areas, this might be required by code anyway. I think steel hurricane ties should be used for trusses no matter where you are, and whether required by code or not.

Steel ties require special nails.

When laying out walls, always work from the same corner, so you will know where to find studs later, usually from left to right.

Blocking is required if a wall is over 8 feet in height.

If you are building on a slab, the bottom plate should be treated wood. A sill gasket should be added, or caulking should be applied beneath.

Felling a gumtree c1884-1917 Powerhouse Museum
The way it was doneCharles Kerry or Kerry and Co. via Tyrrell Photographic Collection, Powerhouse Museum / Foter.com / Public Domain Mark 1.0

Framing a preserved wood basement or stem wall is not much different from framing the rest of the house. Extra ties may be required at windows. Blocking will also be required. Definitely check codes and manufacturers recommendations.

You should consider advanced framing techniques. By using some or all of them, you can save considerable material. These methods also make a house easier to insulate well, with less thermal bridging.

Building stairs is also part of the framing if, you are building on a basement, or have more than one story. Most houses will have at least a few steps that need to be built. Building stairs is the subject for a whole article in itself,  so I am just going to include a few links on the subject.          Alternately you can purchase stairs ready made, or ready to assemble.

Building stairs 

Stairs: the next level by Skip Thomsen

Details for conventional wood frame construction–American Wood Council

Construction glossary–Home Building Manual

Share this:
Share this page via Email Share this page via Stumble Upon Share this page via Digg this Share this page via Facebook Share this page via Twitter

Roof choices for your home

Whatever the wall type, trussed rafters are a good choice for the roof framing.

Trusses provide a clear span that makes interior design much more variable, and makes future renovation easier. Trusses can be used in floors as well to provide for a clear span in spaces below. Ease of construction tends to make truss use nearly as inexpensive as other methods. Trusses can be engineered in a great many configurations, and for many roof styles.

a common roof truss

A common gable roof truss

They can provide for vaulted ceilings using scissor trusses, studio trusses, or trusses with center bays. and can be built with “heels” to allow room for more insulation in the attic space It is quite rare to see a house built without trusses, in this part of the country.

Attic trusses can be built to allow for extra rooms under the roof in a story and a half configuration.

Spans can exceed eighty feet with timber roof trusses, although, I can’t imagine many houses requiring that wide a clear span.

You can build your own roof trusses (or as an alternative you can visit www.lamcal.com.au), but they are usually made in a factory setting where they are joined together using steel gang nail gusset plates that are pressed into place. They may include steel structural members. Trusses require careful planning and should be engineer designed or approved. Extra care must be taken here, as this is, perhaps, the most important structural element of your house. You have no doubt all heard of roof collapses, or for that matter bridge collapses. These are often the result of compromised, or under designed trusses. Because the cost is not usually great, I prefer to have trusses designed for higher loads than would normally be required. One way is to have your trusses designed for 2 ft centers, but place them on a narrower spacing.

Your truss supplier will need to know the spacing, span, load, eave width, slope, whether you require a heel, and roof type. If your roof is complicated in any way, they will need a set of blueprints. Load is defined as live load and dead load, where dead load is the weight of the roof itself, including any permanently installed or likely to be installed equipment. Live load is temporary loads likely to be encountered, such as workers and construction equipment, or snow accumulations. Slope is usually expressed as inches per foot such as 4.5/12 or 6/12. A heel raises the rafter portion of the truss, and allows for more insulation at the outside perimeter of the attic.

roof with many gables

Gable roof

Some basic roof types are the gable, hip, gambrel, mansard, pyramid, saltbox, shed and flat. They may be called different names, and come in many combinations, materials and slopes. They are limited only by the architects imagination, structural integrity and the ability to keep out the weather. Needless to say, the simplest   will cost the least. In my opinion, a simpler design  can be more easily blended to it’s environment. A complex roof will add interest, and can make a house stand out, if that is your goal.

Some roof types are better suited for different conditions.

A steeply sloping roof with steel cladding is a good choice in high snowfall areas. Low slope or flat roofs will interfere less with sight lines, and will keep the height of a building down. consider carefully before using a bonnet type roof in cold climates. they have a tendency towards ice damming,

A roof may be clad in many materials but the most common in North America are organic asphalt, asphalt/fiberglass shingles, wood shingles, sheet steel or tile. Tile is mostly restricted to the southern and drier areas of the continent. Wood shingles are usually of cedar and have become expensive enough that they are most often used only where appearance makes them desirable.

A flat roof consists of built up layers of tar and sheet material topped with a protective coating of aggregate, or alternately layers of bitumen or fiberglass waterproof sheet, Not common in housing , it is often used on large commercial buildings. More flat roof info is available at this link.

Roll roofing of organic asphalt is available which is inexpensive and quick to apply, and can be used if economy is the major factor.

A shingle roof, today, is placed on a base of 7/16” plywood, or OSB, with a layer of roofing felt. (I prefer a thicker sheathing.) In cold climates, a layer of self adhesive rubberized material is placed at the eaves to prevent leaks caused by ice damming. Valleys may be further reinforced with rubberized material and aluminum or steel sheet.

Modern asphalt/fiberglass shingles can give pleasing contoured visual effects, and can have lifespans of fifty years or more.This is nearly comparable to wood or steel. Wind resistance is quite good. The economical three tab shingles have a lifespan of twenty five years or more. Some shingles will have additives to reduce moss growth. An asphalt roof must be well vented to prevent excess heat build up. Important on other types, as well, for interior comfort. Proper applicaton is critical. Do your research if you plan to do your own.

man falling off roof cartoon, roof choices for your home

a roof can be dangerous

Steel and tile roofing usually rests on a framework of furring strips. Both may have a better resistance to UV light and heat than asphalt shingles. It may be more difficult to seal any perforations through the roof. Steel has the added advantages of shedding snow easily and of making a lighter roof. Expansion and contraction at differing temperatures is a factor with steel that can loosen fasteners. Steel is very slippery, and venturing onto a steel roof to remove excess snow can be very dangerous. Tiles tend to be fragile, and although walking on a tile roof is possible, it should be avoided altogether if you can.

There are quite a few color choices with asphalt or steel with the most vibrant tones being available with steel. Tile colors are more limited. Dark colors will absorb more heat, and lighter colors will reflect it. There is a considerable difference, and it should be considered when choosing colors. Extra heat can affect the lifespan of some roofing.

Bolder contours can be achieved with tile or steel, but there is considerable variety in asphalt/fiberglass shingles.

Organic asphalt shingles are made with asphalt impregnated paper and a ceramic aggregate. Asphalt/fiberglass shingles are asphalt and aggregate coating on a fiberglass base. They may be laminated (layered) for architectural appeal, added strength ,and and wind resistance. Both have an adhesive strip to bond them together after they are applied.

Roof tiles may be made of differing materials but traditionally are of ceramic or concrete.

From an environmental point of view, there may not be a lot of difference between the choices, when everything is considered. I believe the best thing to do may be to choose a product with a longer life span, particularly where the cost differential is not great. I would like to see someone do a detailed analysis in this regard.

This is a large subject for one blog post. If you would like more information, please use the links I have provided.

For an interesting look at how things are done down under, check out this link

Bill said he couldn’t make any money building a roof——-Too much overhead.

It is snowing heavily outside my window right now, and I am pretty happy to have a roof over my head.

Share this:
Share this page via Email Share this page via Stumble Upon Share this page via Digg this Share this page via Facebook Share this page via Twitter