Hi Laren - thanks so much for the very thorough response - I feel a little like a dufus LOL - I should have thought to go to the lumber yard and get a materials quote...
I do understand the structural issues and they will be taken into consideration....
Solar gain is not going to happen - we need the dormers on the back this is north facing...We heat with wood and have great solar gain in the downstairs and the upstairs stays fairly warm...we are thinking of putting in floor heat downstairs using a solar system....too many projects LOL... Existing walls - interior and exterior are true 4X4 with solid 1X6 down the full wall...old house....yes there is a center support wall down the house...I will for sure connect with someone to engineer this project to take into consideration the things you wrote...
great help here - thanks everyone...
aliza
--- In DoIt_Yourself@yahoogroups.com, larencorie@... wrote:
>
> Posted by: "songbird97520" songbird97520@...
>
> > - I want to put a dormer in the upstairs of my 1 1/2
> > story farm house. What is entailed in this project?
> > I am trying to do a materials cost estimate so I can
> > even decide if we can do it this year.
>
> Hi Aliza;
>
> You can probably have a local lumber yard put together
> a materials list from a basic drawing. They usually do
> that. However, without details, they will be generally
> guessing, using standard materials.
>
> > The dormer will be either one 30' dormer taking up most
> > of the roof on the back of the house or 3 ~8' dormers.
>
> You need to pay attention to the structural integrity.
> Your roof, now, probably creates a triangle, with the
> floor as the bottom side. That is a stable geometric
> shape, even when the corners are hinged. The new vertical
> wall of the dormer adds another side to it, so that the
> geometry is no longer stable. Pressure (like snow or wind
> loading) on the other side of the roof, will tend to push
> a long dormer over. So, you need to create a new triangle,
> working like only three sides again. If you will have
> a flat ceiling, it can achieve that, by tying the roofs
> together. You can also tie it together with collar ties,
> or a couple of beams. The roof sheathing will provide
> quite a bit of stiffening, but such roofs are still at
> risk of a sagging ridge. You may be able to add ridge
> support, down through walls, to the floor, lower level
> walls, and on down to the foundation. But, you need to
> know how the structure works. So, involve someone who
> understands that kind of thing, and make sure that they
> address these issues, under full design loading. Just
> because it feels sturdy on a nice sunny day, does not
> mean that after a few years of intermittent loads of
> tens of thousands of pounds from wind, snow, etc, that
> it will not begin to develop a sagging ridge. I know
> of a few houses that have added dormers, which now
> have saging ridges, and slightly out-tipped dormer
> walls. So remember; if it is not a triangle (or the
> sturdy, unhinged, extension of one) so that it can
> bear the roof loads on the exterior walls, then it
> needs to have bearing posts (or walls) under it,
> to carry the load down to an interior foundation.
>
> > Dormers will be about 6 feet deep and just simple
> > shed dormer on the back of the house. House is 40'long.
>
> The tip-up roof dormer, that was suggested, will work.
> Just be mindful of structural issues.
>
> > I am not talking about foundation support or interior
> > wall issues.
>
> Again, it may be advantageous (and even easy) to add
> interior ridge support down through walls. It is likely
> that there is an interior bearing wall, on the main
> story, basically running down the middle, under the
> ridge. If the main floor is over a basement or crawl
> space, there is likely to be another beam, down the
> middle of it.
>
> You can also use this opportunity, and additional
> space, to upgrade the energy performance of your
> home. If you fur down the ceilings, to provide a
> space for 12-16+" of insulation, you can have it
> blown full of dense packed cellulose, which does
> not require roof venting. Use at least 2x6s in
> your new exterior walls. The walls can also be
> dense packed with cellulose. Cellulose is not
> expensive, and it is often cost no more to
> have it installed professionally, as to
> do it yourself.
>
> Another energy area is your windows. If they
> face South, they can have a positive energy
> effect. If they face North, they will lose a
> lot of heat during the heating season, without
> gaining heat from the sun. This difference can
> be around 200,000 BTU (several dollars of propane),
> per year, per square foot of window. East and West
> facing windows are another issue. They do get some
> Winter sun, but their problem is the large amount
> of Summer sun they get. So, if you have a choice,
> put the dormer, and its windows facing South.
>
> Laren Corie-
> Natural Solar Building Design
> and consultation, since 1975
> www.ThermalAttic.com
>
> Read my Solar house design articles in:
> -Energy Self-Sufficiency Newsletter-
> www.rebelwolf.com/essn.html
>
> Home base-LittleHouses YahooGroup
> http://groups.yahoo.com/group/LittleHouses/
>
> Founder-WoodGas - Power from wood
> http://groups.yahoo.com/group/WoodGas
>
> Founder-RefrigeratorAlternatives YahooGroup
> http://groups.yahoo.com/group/RefrigeratorAlternatives
>
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