Sky­light re­moval likely means big­ger job

Winnipeg Free Press - Section F - - HOMES - ARI MARANTZ

QUES­TION: I read an ar­ti­cle of yours online and pub­lished in the Free Press about re­mov­ing sky­lights. We bought our home a year ago. We are just about to get our roof re-shin­gled and have de­cided to re­move two old sky­lights that were in­stalled back in the ‘80s.

Our house is a one-and-half­s­torey built in 1930. The two sky­lights are each two feet wide by four feet long and are lo­cated in the sec­ond-floor mas­ter bed­room, on the por­tion of the ceil­ing be­tween the apex and the knee wall. The roof/ ceil­ing has a very steep pitch. The house has been ex­ten­sively ren­o­vated with all new Gyproc through­out and the at­tic has been in­su­lated with thick fi­bre­glass bat­ting. How­ever, we don’t know what’s been done to in­su­late the sloped part of the ceil­ing, where the old sky­lights are lo­cated.

I’ve read your ar­ti­cle, which is very help­ful, but I’m won­der­ing if there is any­thing in par­tic­u­lar we should know about in­su­lat­ing the open­ings once the roofer has in­stalled the sheath­ing. In this par­tic­u­lar sit­u­a­tion there is a sloped ceil­ing with un­known in­su­la­tion be­hind the Gyproc.

Also, is there any­thing we should be mind­ful of be­fore we have light­ing in­stalled where the old sky­lights ex­isted? Nicky Pringle.

AN­SWER: You have iden­ti­fied an area that is nor­mally tricky to deal with when do­ing ren­o­va­tions. I think you have the right idea to re­move the old sky­lights, but run­ning elec­tri­cal wiring and in­su­lat­ing this space may lead to some dif­fi­cult de­ci­sions on your part. Your ques­tion is one that is com­plex and the so­lu­tion may be a larger job than you imag­ined.

The sloped sec­tions of older 1-½-story homes of­ten pose a dilemma when you want to prop­erly in­su­late and ven­ti­late your at­tic spa­ces. Be­cause there is lim­ited space be­tween the ceil­ing and the roof sheath­ing — of­ten less than four inches — de­cid­ing on whether to re-in­su­late this space when do­ing up­grades can be prob­lem­atic.

If you do open the space to use con­ven­tional in­su­la­tion and air/vapour bar­ri­ers, how can you put in any ven­ti­la­tion? Is four-inch fi­bre­glass bat­ting enough in­su­la­tion to pre­vent ex­ces­sive heat loss through this space? Will this be a sub­stan­tial enough im­prove­ment over the cur­rent in­su­la­tion, which is likely just wood shav­ings or rock wool?

I see many homes like yours where prop­erly com­pleted im­prove­ments to the in­su­la­tion and ven­ti­la­tion of the knee-wall at­tics and the up­per at­tic are enough to pre­vent se­ri­ous ice damming and mois­ture is­sues. It’s of­ten not pru­dent or nec­es­sary to re­move the en­tire sloped ceil­ings just to prop­erly in­su­late and seal the cav­ity be­hind. While any in­su­la­tion in this area will pre­vent good air flow and ven­ti­la­tion be­tween the up­per and lower at­tics, re-do­ing the in­su­la­tion with­out ma­jor up­grades may not yield any im­prove­ment.

Re­mov­ing the sky­lights will only serve to pre­vent some heat loss through the glass or around the curbs, but will not sub­stan­tially im­prove any­thing else in re­la­tion to ven­ti­la­tion. For that rea­son, I sug­gest that you go with larger ren­o­va­tions to im­prove the sit­u­a­tion sub­stan­tially.

I rec­om­mend that you re­move the en­tire sloped sec­tions of the ceil­ings in the up­per-floor bed­room, not just the sky­lights. This will al­low you to in­spect the fram­ing around the sky­lights to see if there is any mois­ture dam­age. The fram­ing and the roof sheath­ing around the sky­lights could be fairly rot­ten with­out be­ing vis­i­ble from above or be­low.

Once the con­trac­tors are up on the roof re­mov­ing the sky­lights and roof­ing, it can be dif­fi­cult to de­lay the roof­ing in­stal­la­tion if ma­jor dam­age is seen. Roofers try to re­place shin­gles the same day as the old ones are re­moved, to pre­vent pos­si­ble leak­age from a sud­den rain­storm. If this is de­layed, while rot­ten fram­ing or sheath­ing is cut out and re­placed, wa­ter dam­age from rain is much more likely.

To pre­vent this po­ten­tial hazard, re­pair­ing dam­aged roof com­po­nents prior to re­moval of the sky­lights would be pru­dent. By sim­ply re­mov­ing the dry­wall on the ceil­ing, and any in­su­la­tion be­hind, mois­ture dam­age would be read­ily vis­i­ble. Any dam­aged rafters could be re­in­forced or re­placed, and new fram­ing re­quired un­der­neath the sky­lights could also be banged up be­fore they are taken out, fur­ther speed­ing up the process. The un­der­side of the roof sheath­ing could be in­spected and probed, so that the ap­pro­pri­ate amount of re­place­ment ma­te­rial could be brought on site and avail­able when the roof­ing job com­mences. This will also al­low some elec­tri­cal work to be roughed-in, due to the newly ac­ces­si­ble fram­ing.

Open­ing up the en­tire sloped ceil­ing will also al­low more and bet­ter in­su­la­tion. If you fill the old cav­ity with blown-in, high-den­sity polyurethane foam or well-sealed ex­truded poly­styrene sheath­ing, you will have a rea­son­able amount of in­su­la­tion. But you could im­prove upon that even more by tak­ing down the dry­wall and in­stalling ad­di­tional rigid in­su­la­tion un­der­neath the rafters, bring­ing the in­su­la­tion lev­els much closer to that in the rest of the at­tics. This would also in­su­late the bot­tom of the rafters, pre­vent­ing heat loss due to ther­mal bridg­ing. While you would for­feit some head­room, the ad­van­tages would out­weigh the loss of space.

Your need to in­stall elec­tri­cal wiring and fixtures clinches the case for in­su­lat­ing the en­tire sloped ceil­ing, since you will have to re­move ad­di­tional dry­wall for that task,

Ari Marantz is the owner of Trained Eye Home In­spec­tion Ltd. and the Pres­i­dent of the Cana­dian As­so­ci­a­tion of Home & Prop­erty In­spec­tors - Manitoba (www.cahpi.mb.ca). Ques­tions can be e-mailed to the ad­dress be­low. Ari can be reached at (204) 291-5358 or check out his web­site at www.trained­eye.ca.

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