Weather protection: the secret for you house health

To build a new house is not a big deal itself. Of course is a very demanding job, but if you are an organized person and like to control budgets you can do small projects by yourself. The difficult part is to work on building process and renovation projects that are expected to last forever. Or, at least, for the next 50 years.

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A good roof project can help a lot your house to be protected from water infiltration

Having in mind this concept, one of the most important topics here is moisture and water. Regardless if you are an experience builder or not, water will find its way to penetrate a house. It doesn’t mater also the type of exterior finishing you are using (PVC, vinyl, wood, fiber cement, stucco or even metal). Instead of fighting against this reality, you have to think about water getting away from sheathing and framing.

  • Create a water resistant barrier (house wrap your house – it will be the “rain coat” to protect the water to enter the walls)
  • Put in your plans a roof overhang of 12 inches at least (is like an umbrella for your walls – if you don’t have it, the only protection will be the “rain coat” and you will need a great one if your goal is to stay dry)
  • Choose a 1 story house (the amount of water pouring in the wall will be much less compared with a 2 or 3 story house)
  • Avoid shallow-pitch roofs
  • Use good quality materials for your exterior walls
  • Carefully look for wrap products that can be a potent barrier for water

We like to use in our projects the Zip Wall sheathing from Huber. In projects that use Hardie-Plank materials you can use some strips to help in the water barrier. You have a lot of products that can be used also, but it depends on the specificity of your project.

If you need more information, don’t hesitate in contact us

 

Save money with roof trusses

With the decreasing availability of large structural lumber work with trusses for your roof construction can save you money and also comply with all structural needs for your project. The length of lumber subject to bending stress are broken into smaller sections, and that’s the main reason you can work with cheaper lumber products. But take care of some extra costs when doing trusses for your roof.

Image result for trusses types
Photo credit: click HERE

You have a lot of types of truss designs, and during the design of your project you have to adapt all your load needs. The maximum allowable span depends on the type of wood you are using in your construction (Southern Pine, Douglas-Fir and Spruce Pine-Fir – also known as SPF – are the most common) and also on the pitch of the top cord.

You have some places in the internet to help you on calculating the allowable span for trusses in your project. Click HERE to redirect you to one of these websites.

A final message: remember that in the majority of the houses you will be building with roof trusses you’ll need a crane to help one the truss installation. The costs will vary from region to region, and for a house around 2,500 sf, ranch style, you will need at least 8 hours of crane work if you have a trained team to installed them. Don’t forget to include this cost in your project.

Keep the quality on your roof edges

APA – The Engineered Wood Association has a lot of useful information for builders in their website, and here we will share a very important tip: how to choose your panels for soffit applications.

Quality APA panels are a great alternative to other materials used in soffit applications. There is a variety of APA face grades from which to choose. Selecting the appropriate panel depends primarily on whether the soffit is open or closed.

For appearance purposes in open soffit construction, you have to provide adequate blocking, tongue-and-groove edges, or other edge support such as panel clips. Minimum capacities are at least 30 psf live load, plus 10 psf dead load.

For open soffit construction (figure 1), panels designated Exposure 1 may be used.

Figure 1 OpenSoffit

Exterior panels should be used for closed soffits (Figure 2).

Figure 1 ClosedSoffit Wise Home Building

In open and closed soffit construction where Exposure 1 sheathing is used for roof decking, you have to protect panel edges against direct exposure to the weather with fascia trim.

Fascia Subfascia plan drawing Wise Home Building
Plan drawings showing a fascia, sub-fascia and trim to protect the edge of a roof (red arrow) in an open soffit design

Finishing. Although unsanded and touch-sanded grades of plywood are often used for soffits, optimum appearance and finish performance is achieved by using panels with Medium Density Overlay (MDO), or textured (such as APA 303 Siding) or sanded A-grade faces. Top-quality acrylic latex house paint systems perform best and are the only systems recommended for A-grade faces.

You can find more information in the APA website: www.apawood.org/

Keep the quality on your roof edges

APA – The Engineered Wood Association has a lot of useful information for builders in their website, and here we will share a very important tip: how to choose your panels for soffit applications.

Quality APA panels are a great alternative to other materials used in soffit applications. There is a variety of APA face grades from which to choose. Selecting the appropriate panel depends primarily on whether the soffit is open or closed.

For appearance purposes in open soffit construction, you have to provide adequate blocking, tongue-and-groove edges, or other edge support such as panel clips. Minimum capacities are at least 30 psf live load, plus 10 psf dead load.

For open soffit construction (figure 1), panels designated Exposure 1 may be used.

Figure 1 OpenSoffit

Exterior panels should be used for closed soffits (Figure 2).

Figure 1 ClosedSoffit Wise Home Building

In open and closed soffit construction where Exposure 1 sheathing is used for roof decking, you have to protect panel edges against direct exposure to the weather with fascia trim.

Fascia Subfascia plan drawing Wise Home Building
Plan drawings showing a fascia, sub-fascia and trim to protect the edge of a roof (red arrow) in an open soffit design

Finishing. Although unsanded and touch-sanded grades of plywood are often used for soffits, optimum appearance and finish performance is achieved by using panels with Medium Density Overlay (MDO), or textured (such as APA 303 Siding) or sanded A-grade faces. Top-quality acrylic latex house paint systems perform best and are the only systems recommended for A-grade faces.

You can find more information in the APA website: www.apawood.org/

Understanding your roof parts

Roof terms are a little bit complicated, and here you can check if you are familiar with them.

The pitch of a roof is the vertical rise divided by the total span. The slope is the vertical rise divided by the horizontal run (a run corresponds to half of the spam). Imagine that a building has a roof peak located 8 feet above the top plate. The building width is 24 feet (total span, in roof words). So, the pitch is 1/3 (or 4 in 12 – normally the plans shows multiples of 12). The run is half of the span (in that case 12), so the slope is 8/12 (or 8 inches of rise per 12 inches of run)

Framing a Gable Roof
Diagram from the website https://www.mycarpentry.com

The pitch defines the angle of the roof in degrees – a 12″ in 12″, for example, corresponds to a rood with an angle of 45 degrees in the lateral side (an eave, in the rood language). It is very important to understand this concept to work together with your framing team to define the loads of your roof, mainly in our area, where snow times during winter can be tough. The main areas of your house will need pitches of at least 8″ or 10″ in 12″. Deck ceilings can have less pitch in the roof design 2″to 4″in 12″).

roof pitch expressed in degrees
Photo credit: https://www.roofingcalc.com

To understand the other names associated with your roof area, check the photos from the website https://www.mycarpentry.com. They also have a calculator to facilitate the roof analysis during your building process.

 

Snow Loads on Roofs: take care of it

How much snow can a roof support? It depends on the way you design it.

Image result for roof with snow
Photo credit: click here

780 CMR Commercial Mass State Building Code Table 1604.11 provides snow load for roofs. The Ground Snow Load ranges from 45 lbs to 65 lbs per horizontal square foot depending on each community and the zone in which it is located. The Residential Code 5301.2(5) for 1 and 2 families’ ground snow ranges offer different values again depending on the community and zone of 25 lbs. to 50 lbs. per horizontal square foot. To determine the snow load for your specific community and zone refer to the chart.

A flat roof, gable roofs and roofs with multiple valleys and snow gathering points will vary the weight differential factors as will the number and type of roof coverings effect the value. First we have to presume that the structure has been constructed to sustain the minimum snow load requirements of the code.

The weight of snow/ice, not the depth, is critical in assessing a roof’s vulnerability. The water content of snow may range from 3% for very dry snow to 33% for wet, heavy snow to nearly 100% for ice. An inch of water depth weighs 5.2 psf. Thus, a roof designed to a carry a snow load of 20 lbs per horizontal square foot is expected to support nearly 12 inches of wet, heavy snow. If using the heaviest wet snow value for roof designed to sustain 40 psf of snow load then it can be viewed that it should be capable of supporting nearly 24″ inches of wet heavy snow. If the snow moisture content is less, the depth of snow for sustaining can be greater.

Please use this information as a tool to assist you . If you need more precise information please contact a structural engineer to measure your roof loads. Roof failures may not be solely attributed to built up snow, there may be other actions that occur that affect the roof structural stability and sustainability.