We are converting our screened-in porch (12x13ft on the existing 4' deep concrete slab) into a 3-season room (with insulated windows, 3'ft wall, and an insulated door.) The enclosed porch has a flat roof with deck (balcony) on top.
We live in the extreme weather (heat/humid/ wind/ & cold) of Chicagoland. Hence, insulation and condensation are always our key concerns. As far as building experience, we are totally intimidated when dealing with exterior structure. What is the best way to insulate the enclosed porch and avoid mold problem in the future? Should we put a house wrap or foam sheaths on the exterior framing before putting on the insulation bat in between the wall cavities? We plan to use PT plywood (not siding) as the exterior wall though. Also, would the PT plywood being exterior wall whist having gypsum sheathing for interior wall appropriate for the circumstance? We haven't put much thought into the floor insulation just yet. Sigh. Thought an area rug will do for the time being. =P Thank you for reading and for your advice.
Your questions would indicate that you may be biting off more than you can handle. What you are asking pretty much covers the whole “building envelope” idea. I do not know the exact building requirements in Chicago, so if I was you, I would find a reputable designer or supplier that could walk you through the insulation requirements. I assume a 3 season room means you will not be using it in the winter months. Does this mean you will not be heating the room? If you are not heating it, then the insulation requirements really are not that important, since you are not using energy to heat and retain the heat in the room.
In our area, Kansas City, the floor requires a R-19 (6”), and the ceiling requires a R-38 (11”) plus the ventilation area. Check out a foam product called Icynene. This product requires less thickness to deliver more R value and since it is closed cell, it does not require any air space. Conventional insulation requires ventilation to minimize condensation.
Un-insulated concrete slabs are very difficult to keep comfortable in cold climates, since concrete is a very conductor of heat and cold. Have you considered a heated floor. They make these types of rooms very toasty on those chilly days. Here’s a link to a flooring company we use - warmlyyours.com
Re-insulating a botched 4 season room
I'm reinsulating between 2x8 floor joists of a 4 season room that wasn't done properly.
It is almost at grade level, no access to underside of joists. Am putting full 1" x 1" strips on each side of joist flush with bottomm of joists. Then I am putting 1/2 inch wolmanized lumber down on top of these rails with screws. Then I want to put r19 kraft faced insulation, faced side up to floor.
Am I doing this in the right way and do I need to be concerned about trapping any moisture? Ventilation needed? I will be adding a cold air return, another hot air vent too for a total of 2. The other existing vent was not run back to main plenum. Also adding a gas pipe for a gas fireplace.
The way you are installing the insulation sounds like it will work.
All "crawl spaces" must be ventilated to help control moisture. The crawl space should have some sort of covering over the soil as well, like a 6 mil plastic sheeting. I know this could be hard to do if there is no access. You might be able to do it when you are installing the wood to hold the insulation in place. This will help contain the moisture and minimize the amount of moisture that can rise from the moisture in the soil.
Is there anyway you can add some ventilation, at least one on each corner? If you can accomplish these two items, you should be in pretty good shape.
Insulating the floor
I am adding on a new 3-seasons porch. I will add a gas line for a fireplace as well and since the furnace room is so close, may run ductwork out there in the future.
The 11'x20' porch will have a gable roof tied into the house w/single hung windows and 2 doors all around. It is being built over 1/2 existing concrete patio and 1/2 lawn. There will be about 18" for joists underneath.
I live in ND with extreme temps and last year tons of snow melt. To prevent moisture/mold will plastic with rocks over the grassed area suffice? How do you seal the perimeter from snow melt/rain? Green treated lumber dug into the ground a bit? I have a contractor but he wasn't going to put any plastic down and said it would be fine. The inspector suggested it. What would be the best way to insulate the floor? I was thinking plywood under the joists, seal all with that expanding foam sealer and foamboard insulation? Thanks in advance for your expertise. I truly appreciate it. Valerie
You might want to consider using treated joists. At 18” and less the code requires it. By using treated lumber you minimize the chances of rot and insect problems.
Definitely put a 6 mil or thicker plastic over the soil and patio, with a minimum of 2” of gravel. This will help to reduce moister from permeating the floor system.
You should use some sort of treated lumber to seal around the perimeter of the room. The code does require that these crawl spaces be ventilated year round. For the size of room you are constructing, you will need 2 vents at least 1 square foot each.
The 2006 International Residential Code calls for an R-30 floor insulation. Anytime you use batt insulation you should also provide for ventilation. This reduces the chances of mold forming.
I hope you are using a professional designer to take into account these issues. In the long run, you will have a very comfortable room to enjoy those North Dakota winters in.
Flooring for the seasons
Question from Paul:
I have a three season room which is built on beams (possibly an old deck. 4x4's sitting on concrete pylons). It currently has 3/4 inch plywood floors covered with outdoor carpet. My question is what kind of floor replacement do you recommend? I want to get away from the carpet if I can. I would like to put a wood or tile floor down but don't know how it would hold up with the temp changes. In NJ we have hot humid summers and cold winters. I do have a heater installed but only use it when we are in the room.
It sounds like your climate is similar to ours in Kansas City. Basically you have a room that is exposed to the extreme temperature and humidity changes, so you need to be careful of the type of flooring you put down. A wood floor would probably not work too well, too much exposure to the elements. I would suggest putting down a tile floor. Assuming you can use the existing plywood as a sub floor you will need to add a cement type underlayment. The best type would be a 2” mud set base with the tile on top of it. If the increased floor height causes a problem then switch to a ½” concrete board, like Durock, check it out here.
You can then install the tile over the Durock. If you are concerned about the cold floor you can add some area rugs for comfort.
Interior finishing for a four-season porch
Question from Carole:
What is the best interior finish for a 4 season porch. I have been told that drywall should be avoided. I live in Michigan.
By a 4 season porch I assume you must be referring to a porch that is opened to the elements. If the porch is not opened to the elements, drywall would work fine. If opened, I suggest a fiber cement product manufactured by James Hardie. You can get lots of information on it at JamesHardie.com These panels come in various sizes and textures. It is a very durable, it is paintable and it even comes in pre-finished panels.
Converting a 3 season room to a 4 season room
we live in Wisconsin and have a nice 3 season room. However, can it be changed into a 4 season room and what is an estimate of the cost?
That's a tough question to answer. I assume by changing to a 4 season room, you want to be able to use the room year round. This would mean heating and cooling the room - at least heating. Once you decide to heat the room, you must address the insulation, doors and windows, and how to get heat/cooling to the room. The only way to accurately estimate this is to have a professional remodeler visit your home and look at the current situation and then determine the steps to make it a comfortable space year round. Some of the conversions we have done have been in the range of $25,000 to $45,000.00.
Converting porch floor
A part of our house has had a cement pad added in the past as a porch then enclosed to make it part of the living space. It is about 4 inches below the grade of our floors in the regular part of the house and I want to bring the cement part up to the same level as the other part. Do I custom cut 2x4's and make joists that will fit over the cement and then put on my sheeting to bring both floors to the same level? Or do I remove the cement floor and dig out enough space to put in the proper size joist to span the 9 feet and cover with sheeting? What about vapor barrier or venting? How do I get heating runs put in the floor? What do I really need to do here?
We have converted several porches that were built over concrete slabs into living indoor living spaces. What we typically do is put a vapor barrier over the concrete, like a 6 mil plastic and then custom cut treated lumber to act as joists and these joists rest directly on the concrete slab. The 3 ½” space between the slab and top of the new joists will allow you to run some ducts to heat and cool the space. Insulate the joists space and install ¾” plywood over the joists.
This is all based upon the concrete slab being adequate to build on. It should be a minimum of 4” thick with a thickened edge around the perimeter.
Good luck and good remodeling.
Converting a 3 Season room
Would it be costly to turn our three season porch into a four season porch?
That all depends. There are a whole lot of factors to consider. The biggest being the heating and cooling of the room and trying to keep that high dollar energy trapped inside. This really boils down to the quality of insulation in the floor, walls and ceiling. Take a look at the quality of your doors and windows as well. If these items can match the building code requirements for your area without costing you and "arm and a leg", I would say go for it. Contact a reputable remodeling company in your area to help assess your current situation. Go to www.nari.org for help in finding a good company in your area. Best of luck to you! Jake