You have OSB as your roof sheathing. Do you cheer or panic?

That depends on what grade the OSB panels are, and whether the right panels were installed.  OSB (which stands for Oriented Strand Board) is a variant of plywood, and is an engineered product, meaning that each type of OSB panel has defined end-use and method of application.  Information on the types of panels and their uses can be found here:  http://www.apawood.org/level_c.cfm?content=pub_osb_libmain

The panels are manufactured in two grades: Exterior and Exposure 1. “Exterior panels have bonds capable of withstanding long-term exposure to weather.”   The Exterior 1 grade “is intended to resist the effects of moisture due to constructions delays or conditions of similar severity”.  Which means that if the OSB panels have been installed as roof sheathing, then a few days exposure to the weather is permissible before the tar paper or other underlayment is installed.

If the roof panels  are Exterior grade, then you have nothing to worry about.  Most of the panels installed as roof sheathing, however,  are Exposure 1 grade,  which means they CANNOT be exposed to long-term moisture.  That is fine, as long as the roof doesn’t leak, or condensation doesn’t happen.  Leaks, when they do happen, generally start gradually, and it may be several years before a leak is detected.  By that time, the OSB has been exposed “long-term” to weather (which in this context, means water), and therefore the glue holding the wood chips (strands)  together starts to dissolve.  This leads to the weakening of the panel, as well as causing it to swell and buckle with absorbed moisture.  Persistent condensation will do the same.

In short, if you have Exterior grade OSB, you can change your roof when it’s due – the panels should not be affected.  If you have Exposure 1 grade, then you should carry out a regular program of attic inspection to ensure that no water is getting in.  Otherwise, the cost to reroof may have to include the cost to redeck the roof, and do whatever mold remediation that is necessary.

OSB damaged by persistent leakage, being removed.  Note the dark stains in the insulation.  It too will be removed.

OSB damaged by persistent leakage, being removed. Note the dark stains in the insulation. It too will be removed.

From another installation / repair, we had very localized leakage, but it ended up ruining that piece of OSB.

Damaged OSB.  Leakage was localized but still need to be redone.

Damaged OSB. Leakage was localized but still need to be redone.

If you’re not sure of what you have, or if you know you have OSB but aren’t use what state it is in, give us a call.  We’ll do an inspection and tell you our opinion.

(c) 2013 Paul Grizenko

It’s winter. And you have a roof problem. Now what?

In Quebec, winter provides all kinds of challenges to your roof, from freezing rain, to severe temperature changes, to strong winds, to very cold temperatures, to snow accumulation, to rapid  ice/thaw  cycles.  With the climate change that we are all living through, the weather extremes become more pronounced and more frequent.  If your roof is not well-designed and well-installed, the weather will find the roof weaknesses, and you WILL have problems.

In winter, the most immediate problems are usually leakage and ice damming.  The longer-term dangers are caused by leakage, condensation, and snow accumulation.  Sometimes, wind can damage poorly installed flashings or soffits.

If you have leakage, there are a number of possible causes:

  •  ice-damming,
  • caulking failure,
  • flashing failure,
  • underlayment or membrane  failure,
  • failure of waterproofing seals,
  • incorrect choice of vents and vent positioning,
  • aging of key components that no longer keep the water out,
  • fastener seal failure,
  • blocked valleys,
  • blocked gutters,
  • internal condensation
  • and other causes that are not as common.

The first step is to figure out why you have a leak when you had none before.  As can be seen from the above list, there are many things that can cause an apparent leak.  Each possible cause has its own set of diagnostics, and leaping to conclusions usually ends up costing money and doesn’t fix the problem.   Finding a leak can be particularly challenging if the roof system was not well built, or if the water has travelled along the vapour barrier.

Ice Dams can appear even with well-built roofs, if the conditions are just right.  However, they usually signal a combination of insufficient insulation and ventilation.  Older homes, built under codes that were not as stringent as they are now, often have ice dams and massive build-up of icicles decorating the roof eaves.  Once the water starts building up behind the ice dam, it is under pressure, and enters any opening, crack, or gap.  If the waterproofing is not perfect, you have a leak.  If the roof was built with multiple levels of protection, then the water at the ice dams usually stays outside, but if there is only one layer of protection (typical of cheaply-built roofs), then there is no margin of error.  Any failure in that one layer will result in a leak.

Occasionally, “leaks” are caused by condensation.  How is the moisture getting into the attic or cold spaces in the first place?   We find any number of reasons when we start looking for causes – but almost always, it is due to some error in venting, or in a seal that is no longer working.  We’ve seen bathroom renovations where the contractor directed the air vent from the bathroom directly into the attic, and more than one case of clothes drier vents being installed with their outlets inside the roof system.  We’ve also seen home renos where the potlights were installed in ceilings without the proper sealing, and ended up causing massive amounts of condensation by letting in the air from the living space into the cold spaces.

So, what do you do when you think you have a leak?  Call an expert – we’ve seen more of the underlying causes and reasons than you ever will (unless you are really, really unlucky), and we’ll know where to start looking.  Depending on what we find, we may be able to fix it quickly, or we may suggest some temporary measures until we can fix it properly once the snow is off the roof in spring-time.  Under extreme situations, we can (and have) rebuilt roofs in winter, so it is possible to do, but it can get expensive.

The best way to not have these problems, is to make sure all the fundamentals are working correctly.  That means ensuring that your vapour barrier is effective and complete, that you have enough insulation of the right type, that your ventilation is set up in a manner appropriate to your style of home, that there is the right amount of waterproofing (membrane and seals) in all the places where water can appear, and that there is the right layering of protection (membrane, underlayment, flashings, caulking) in all the susceptible areas.

Your home is your most important investment.  Shouldn’t you have the best protection for it that you can have?

If you’re not sure you have it, contact us and let us arrange an inspection.

(c) 2013 Paul Grizenko

Ice dam as seen on the outside - lots of icicles!

Ice dam as seen on the outside – lots of icicles!

Image shows leakage and persistent wetness of the decking.  Water has entered insulation and the gyproc underneath.

Image shows leakage and persistent wetness of the decking. Water has entered insulation and the gyproc underneath.

If we only knew then, what we know now…

Knowledge is a precious commodity.  It is usually appreciated after the consequences of the lack of knowledge become apparent.  If we only knew then what we know now…

There are, of course, various time-honored strategies for dealing with this.  One is blissful ignorance.  Another, related to the first,  is wishful thinking.  Still another, is finding stuff out on the internet, which bring to mind the admonition that a little knowledge is a dangerous thing.

This blog will share some of the insights that I have had over the almost two decades of working with people on their roofs.  The blog will look at actual examples, and discuss the lessons that can be learned.  It will explore the concerns and preoccupations of homeowners who are trying to ensure a solid roof over their heads.  And it will, if the interest is there, discuss what seems to work, and what definitely doesn’t.