Lstiburek Perfect Roof

There is no potential for condensation until interior moisture levels exceed 45 rh at 70 f during the coldest month.

Lstiburek perfect roof.

Here s a wall diagram to whet your appetite. Houses didn t used to rot but too many of them do now. Lying down it makes the perfect slab. Joe lstiburek talks about enclosure design principles for energy efficient houses.

The first control layer is for bulk water or liquid water redundant terms used to make a clear distinction between water and water vapor which is the third control. All insulation above roof deck the big deal with unvented roof assemblies is to control condensation or moisture accumulation on the underside of the roof sheathing. The perfect wall roof and slab building science podcast dr. R 46 unvented roof assembly two layers of r 6 5 inch rigid insulation yielding a total combined thickness of 2 5 inches.

Two layers are preferable to one layer due to increase in air flow resistance. There s been so much stuff said about roofs that you sometimes lose perspective. Simple physics complicated language. The biggest benefit of the pmr is that the membrane is well protected.

If all of the insulation is on the top of the roof sheathing this is pretty much a no brainer. That is one of the neat ideas of lstiburek s perfect wall. Cost aside the most straightforward route is spraying closed cell polyurethane foam on to the underside of the roof deck. I ve been thinking about this concept for years but i m finally building a perfect wall house.

The physics doesn t change with floors or roofs so to get the perfect roof just pitch the wall same for the slab. One of the great features of these systems is that the water control layer is also the assembly air control layer and vapor control layer a k a the perfect roof see bsi 001. Lstiburek s commitment to advancing the building industry has had a lasting impact on building codes and practices throughout. But stay tuned for the perfect wall austin blog posts next week.

Tilted it makes the perfect roof. The perfect roof the perfect roof is sometime referred to as an inverted roof since the rainwater control layer is under the insulation and ballast i e. Unvented roof here again the choice of what insulation to use and whether to install it over or under the roof deck depends on the condition of the present roof the depth of rafters the r value you must attain and cost. Joseph lstiburek is the founding principal of building science corporation.

Joseph lstiburek talks about the not so controversial ways to maximize the efficiency and airflow of your roof and attic.