Siding alignment with exterior insulated foundation.
MAK41
| Posted in Construction Techniques on
For the ones who didn’t see my intro from before; I am not a pro but we are getting ready to bid out a new build, single story home over a full utility basement. (There will be a walk out side and that wall will be framed 2×6 to allow for future egress window installs and rooms to be framed in that end of the basement.)
For energy conservation reasons, allowing for a dramatic downsizing of the geo-thermal HVAC unti, we’ve gone with an external foundation insulation system which will allow for 2″ (R-10) ridged foam with drain board and native soil backfill. All good so far.
The extra thickness of the foundation has raised an eyebrow or two in trying to decide how to get the cedar shingle siding to properly overhang. Any suggestions?
Replies
Well, it's not hard to understand that you don't want the top edge of the foundation exposed -- somehow the siding needs to lap the foundation.
There is a term (that excapes me at the moment) for a board that sits on the foundation, has a sloped outer corner, and "mates" the siding and foundation, even though the foundation is "too far out". This is a possible choice if you're desperate, or if the style (an old-fashioned look) just happens to match what you're looking for, but not generally a good choice otherwise. (Would probably be fairly durable if done with modern plastic trim products vs the traditional wood.)
A hair better than that: You will sometimes, on older homes, notice that the siding angles outward for the bottom foot or so, to spread out over the edge of the foundation. Again, maybe not the "look" you want, but an option (especially with shingles, where the "look" seems to fit better than with plank siding).
Otherwise you want the wall to be positioned on the foundation such that the face of the siding is out past the edge of the foundation (including insulation) slightly. "Slightly" here is a half inch or an inch (again, depending in part on "look" issues, plus how much irregularity in the wall and foundation you need to hide).
Normally, if using shingles or plank siding, you'd have the bottom edge of the siding also end a half inch to an inch below the top of the foundation (kind of waving in the breeze), to hide/protect the joint. A bit more difficult with steel or vinyl siding, but there are likely edging treatments to do the same thing.
For any scheme you do need to consider how weather sealing is accomplished. Eg, if the siding sticks out a bit then air may get behind any housewrap or other outer wind barrier.
Flare or cap board
Thank you. We do remember seeing houses with a flare outward on the bottom two or three courses. I'll have to look into this more. I'm not sure how this would work at corners with a cornerboard design but knitting the shingles would perhaps be an option. SOmething more to think about. Thanks again.
I think the term DanH was looking for is "Water Table"
Have a look through HOUZZ photos, There are lots of ideas there that you could adapt:
http://www.houzz.com/ideabooks/8094581/list/water-table
http://www.houzz.com/%22water-table%22-foundation
Water Table trim board it is!
See? Ya gotta know the lingo if you're gonna make an impression at the dance.
I looked it up, thanks.
Not sure how the 'ol-timers mounted the bottom courses of shingles to flare out but a Water Table that was tappered like a clpboard might work instead ...?