Deep Dish Retrofits Served Hot by Lstiburek

For those of you considering a Deep Energy Retrofit of a solid masonry home, the folks at Building Science Corp offer a simple paper that covers many of the details that keep Torontonians awake at night. As Dr Lstiburek says in the foot notes, Chris Benedict has been doing DER of solid masonry buildings for years now in NY and is considered a pioneer in the ‘industry.’

Parapet

This is an example of a typical Toronto home parapet. Most homes don’t have this feature, but a combination of rafters of outriggers that prevent good air sealing detailing.

The article falls short of detailing insulation and air barriers at the roof (few residential roofs have parapets), what to do about old masonry chimneys and how to deal with foundation renovation from the outside. Treatment of the latter can be found on the BSC web site when dealing with century old foundations. The ceiling to wall junction as well as chimney detailing however is an issue that needs to be addressed as air leakage and ice damning are significant threats that undermine any DER.

Wall to Rafters

In this East York 1.5 story, the roof rafters bear on the masonry and getting the air tight seal around the rafters at this junction is crucial for a DER.

chimney

Though they add lots of character and reference a period in history, the chimney should be taken down and air sealed at the top floor ceiling height.

The advantages of exterior insulation are that its less disruptive to the occupants and allows the embedded floor joists to stay conditioned year-round. This last point is crucial and the risks especially to the main floor where the untreated wood mud sill is embedded into the masonry

 

Mudsill

Protecting the mud sill from potential rot in an interior retrofit is crucial for durability. See Dr. Lstiburek’s article on this issue.

Toronto homes have masonry going right up to the back side of the roof deck and the ceiling joists and roof rafters punctuate the air barrier depending on where its located for the ceiling. Using the exterior liquid applied air barrier on the face of the exterior brick wall, the continuity at the roof to wall junction might be detailed most successfully with the fewest penetrations if a hot roof is used and the detailing of these points would make for another BCS article!

Click on the link below to read the full article:

 

BSI079_Figure_05_web

Click on the diagram above to read the full blown article on deep energy retrofits of solid masonry homes.