Upgrading Insulation and Ventilation in an existing attic ??
We have a client with a Ranch home 42’x32′ that has the following existing conditions: (see photos attached)
– 2 layers of asphalt shingles over 1/2″ plywood sheathing on top of 2×8 rafters @ 24″ OC
– The roof has a continuous ridge vent + Gable vents at each end wall + a thermostat controlled vent fan on one gable end. There appear to be NO soffit vents
– (3) skylites that need replacing
– Attic insulation consisting of R-19 fiberglass batts installed on top of drywall ceiling that is 2×6 joists @ 16″ OC
– Attic access folding ladder with no sealing or insulation
Client wants to:
– Tear off and replace existing shingles with new asphalt shinges
– Replace the (3) skylites and re-do the drywalled light wells and insulate those light wells to eliminate condensation issues
– Upgrade the insulation in the attic
– Create an insulated cover box for the ladder to stop drafts and energy loss
Questions are:
– Replacing the shingles is easy enough….but do you keep or eliminate the ridge vent? and/or the gable vents?
– We will reframe the skylite light wells and add 2″ rigid foam around the entire assembly on the attic side to eliminate condensation
– Improving the attic insulation?
—Remove all of the existing fiberglass so that we can get to and seal all of the air leaks/penetrations in the existing ceiling and than add r-49 of blown in cellulose on top?
—OR just install 12″ of blown-in cellulose on top of the existing fiberglass. I have a quote for this of $ 1350
—OR spray foam the underside of the roof deck and the end walls with closed cell at 4″ thick…wrapping the rafters at the same time…I have a quote for this of
$ 6500
Thanks in advance!
Jonathan @ DOVETAIL GROUP LLC
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
Jonathan, what did you end up doing? This sounds somewhat similar to my own situation (ridge vents, no soffit vents, upgrading insulation and need to do some sealing).