Expert: Richard Taylor, AIA - 1/21/2004

Question
I have found a great Carl Graffunder home in the upper Midwest that I would love to buy. The price is low as it's a 'fixer upper.' It's on a great lot in an excellent area, but I am totally unfamiliar w/flat roofs and slabs floors in this cold climate. My questions:
* Are flat roofs a nightmare in cold/snowy climates? I received a bid of $35k to tear off and reroof (w/EPDM) this 1800 sq. foot home (includes 9 Wasco skylights, flashing, new insulation, etc.) It has a 10 year warranty. House has a slight pitch. It has leaked previously and I do have some fears of mold in house as a result.
* Will cement walls make the home feel colder?  House has cement block walls w/insulation in them. I did compare them to the plaster walls of my current home ..and the cement block seemed warmer.
* Will cement slab floors be terribly cold in MN? Part of the floors (perhaps 40%) have a heat duct running under them and the floor feels toasty. But am concerned about high heating bills.
* Asbestos removal. Roofer pointed out one asbestos furnace pipe visible on roof. Is it expensive to remove/replace that?
* Plumbing. I do need to check where the pipes run in this type of house. I'm assuming any repair/replacement could be spendy as it might involve tearing up floors or tearing out walls.

Thanks in advance.  

Answer
L Nelson:

Thanks for your question!

The whole reason for pitched roofs is to shed water, ice, and snow; but originally, roofs were always shingled and shingles didn't form an impervious barrier.  With the membrane technologies currently available, low-slope and flat roofs are safely built every day.

But membranes must have integrity to work, and all of the penetrations you've described may compromise the roof's integrity; everywhere you punch a hole in your roof you have to go back and "patch" it with flashing, etc.  If all of this is done properly, however, you'll be fine.  With that out of the way, make sure that there aren't any obstructions to the flow of water and snow from the roof - make sure you have large, open scuppers, drains, etc.  Don't give water a chance to back up on the roof.

Concrete walls will be colder to the touch; how much depends upon how much insulation is in them.  If the interior surface is concrete, you could warm it up by applying an insulation board on the interior and a layer of drywall over.  It's a comfort issue, obviously, and also an energy usage issue.  Your local utility company will almost certainly do a free or very low-cost energy evaluation of the home for you - give them a call.

Concrete slabs lose a great deal of heat through their edges; it's the most important part to insulate.  Depending upon the age of the house, the slab edges may not be insulated at all and you could be losing a lot of heat energy.  The coldness of the slab is a characteristic of concrete as a conductive material.  It'll always radiate heat to the room.  With the underslab ducts, the slab will stay much warmer, and with a warm slab, the room will be more comfortable.  Actually, with all other things being equal, a heated slab will even out the typical temperature swings in the home and may actually reduce the heating bills a bit.

As far a high heating bills, you should be far more concerned with the quality of the windows; insulation in the roof; and the efficiency of the heating system.

Asbestos is rarely a problem in single-family.  You don't typically remove it, you encapsulate it.  It's not likely that there's enough there to worry about.

Unless you have evidence to the contrary, it's likely that the existing plumbing drain pipes are either cast iron or copper.  Both are hardy and long-lasting and shouldn't ever cause you any problems.  Supply lines are likely copper, too.  I can't imagine that hassle of replacing plumbing in a concrete house - it might be easier to build new framed plumbing walls and start fresh!

Well now you know why most homes are framed rather than cast, eh?  A lot of Architects experimented with alternative building systems through the years and while many were architecturally interesting, the fact is that people still have to live in them, maintain them, and occasionally repair them.  That's a lot easier to do in a framed building!  If you're going to buy this house, be prepared for higher than normal costs in every regard.  There's a slip-formed concrete house on my street and the current owners are going through all of these same issues.  But, the house is very unique and that tempers some of the headaches!

Hope this helps!

Richard Taylor, AIA
Richard Taylor Architects, LLC
www.rtaylorarchitects.com