Renovation & Design
Renovation & Design
Installing new layer of drywall over deteriorated plaster a solid idea
Question: I have two questions. My first question has to do with the removal of stipple from the living and dining room ceiling. The house was built in 1950, and the walls and ceiling were drywalled and then plastered. I was thinking about scraping the stipple off the ceiling, then thought I should just put strapping and put 5/8-inch drywall over top of the existing ceiling. Then, I thought I should remove the old drywall and plaster from the ceiling. I have already removed most of the interior walls and it was extremely time consuming. The reason for removing the drywall from the walls is to address the insulation issue. The other question has to do with the insulation in the walls. I know the R-value is not that good and I would either like to add more insulation over top of the existing insulation or remove the old insulation and put in new batts to fill the cavity.
Thanks very much for your answers and direction, Brian B.
Answer: Adding another layer of drywall over top of cracked, deteriorated plaster is the best way to ensure the best, longest lasting job possible and will not require removal of the old ceilings. There may be more than one option for that and insulating your exterior walls, which will also make them better looking and warmer.
Removing stipple from an older ceiling may range in difficulty from moderate to nearly impossible. If the stipple material is older and has been painted several times, removal may be like attempting to scrape concrete off the plaster surface. If it is a newer, thin layer, often sprayed-on, then it makes more sense. If that type hasn’t been painted or modified, it may be easily removed with a standard putty knife or drywall trowel. The simple test for this is to find a small, less conspicuous area and attempt scraping it. If the pebbled finish comes off with minimal pressure, that may be an option before patching and painting.
If it is a typical older type of stipple that may have been trowel or roller applied, then you will find it difficult to scrape even a small area smooth. In that situation, or if you have many cracks or deteriorated plaster surfaces, covering with a new layer of drywall will be a much better choice. There are two typical ways of accomplishing this, but neither should require removal of the old plaster ceilings. You have identified the first way, to strap the entire surface with thin wood strips to allow a good substrate for securing the fasteners for the new sheathing. This is often done on ceilings that are very uneven, no longer straight or level, or where there is major damage or deterioration. This allows the wood planks to be shimmed, which can create a nice straight ceiling over top of a crooked one. It is a good method, but is time consuming and requires costs that may not be necessary.
If your ceiling condition is not too bad, applying a new layer of drywall directly over the old materials may be a simpler option. This will require much longer fasteners and a bit more planning, but will save the complete step of cutting, shimming, and securing the wooden strapping. Before either method is started, the location of the ceiling joists should be marked and the old plaster partially secured with moderate length fasteners. Because of the weight of the old ceiling materials, and older securing methods with common nails, the older surface may have pulled away from the framing behind. Re-securing the older plaster with hardened screws will ensure the new ceiling is firmly fastened and will not sag or crack at the seams over time.
Once the centres of the ceiling joists are located and marked with a chalk line, push the ceiling slightly upward with a brace and drive in appropriate length screws, just below the surface, with a cordless drill or drywall gun. If the plaster is loose, you may create a fair number of new cracks, but these will be of little concern when covered with new sheathing. Once tightened, the old plaster and drywall lath can be completely covered with new drywall, fastened with even longer drywall screws, ensuring that any seams are joined directly over the ceiling joists. This new surface will be much smoother than the older one and will be cosmetically superior, once it is properly taped and sanded.
As far as the insulation in your older exterior walls, the level from the pictures you included seems to be very minimal. A typical two by four wall cavity with batt insulation is usually R-12 to R-14. The small amount of mineral fibre seen in your current situation may be half or less than that total. The paper backing may help somewhat as an air barrier, but does not add anything to the thermal resistance. Complete removal of the old stuff is a no-brainer, but you do have a few options for replacement.
The most common replacement would be with fibreglass batts, which would yield approximately R-12. Upgrading to modern mineral fibre may boost that by a couple points, and using high density polyurethane foam may achieve up to R-20, but the cost will be much higher and will require professional installation. Another alternative would be to increase the wall thickness, simply by strapping the inside of the studs. This would allow you to achieve the higher level of thermal resistance with less cost. It will also more than compensate for the thinner new wall coverings, but will likely require furring out the window and door jambs, which will add to the effort and cost.
Installing a layer of drywall over your old ceilings will allow for a much better product once complete and should be worth the effort and expense. Discarding the old exterior wall insulation and replacing it with new material will help make the house warmer. But making the walls thicker by adding framing on the inside will allow even better thermal resistance, albeit with additional cost and labour.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com
Renovation & Design
Relocating ducts and registers may be worth the effort
Question: When the second storey to my house was added on, about 30 years ago, the HVAC people ran the vents for the second floor through a bedroom on the second floor. These were for the heating system that was in the basement, right next to the chimney. Therefore, this bedroom has a four-foot by four-foot finished box in the centre of the room, six feet away from the outside wall, which contains the chimney and the ductwork. This goes into the attic and from there the heat is piped into the rooms on the second floor. This occurs through small ducts in the ceiling, via flexible tubes that are on the attic floor. We have lived with this for 30 years and now would like to fix this situation, once and for all. Can a gas furnace in the basement be vented out a side wall that is six feet away? If so, we can get rid of the chimney that goes from the basement right up through the roof. Can heating/AC ducts be located on the outside of the building if they are super insulated? What can be done about this situation? I surmise we will have to hire a structural engineer to come up with a plan, but I am hoping that you can give a brief answer so I know in which direction to turn. Someone suggested just leaving the chimney, furnace, and duct work and putting an eight-foot bump-out onto that second floor bedroom. But, I suppose this would be more work and would have to sit on pilings and footings.
I thank you for your time, Martha
Answer: Relocating heating ducts for a forced air heating system can be a tricky job for a home that is already complete. While this may be a worthwhile endeavour, moving them out of the attic should be part of any planned renovation, to prevent issues with condensation and moisture.
A new high-efficiency gas-fired furnace should be able to vent out the foundation or side wall of your home, as long as it is not too close to any existing windows or other restricted items. A licensed HVAC technician or contractor should be able to immediately tell you that by looking at the location. If there is an issue, relocating the new vent and air intake may be possible on an alternate side of the home.
Moving your heating ducts and registers to a new location on the upper floor of your home will make sense once you have upgraded your furnace. This will allow removal of your old chimney, which will give you more unencumbered space in the bedroom in question. As long as the chimney is not supporting any portion of the upper floor system, this should be possible. Evaluation by a professional structural engineer will indeed be required.
As far as installing the new ducting in an exterior wall, that should not be considered an option. In fact, moving the small, flexible ducting from the floor of the attic to interior walls should be seriously looked at. The reason that heating ducts are not installed in exterior walls is that there is no way to properly insulate and air seal them, especially in an older home with minimal space in the wall cavity. Without this protection, condensation on the cold metal ducts in the winter is a given. This could also occur in the warm, humid summer weather, when the ducts are cooled by the air conditioning. This same issue can occur in the attic, but may have been more manageable in the past due to much more space for increased insulation.
Regardless, the best option after removing the chimney and chase is to relocate larger ducts to an interior wall or walls on the main floor. This will be most easily accomplished if one or more of the bedroom walls is common to other rooms upstairs. In that situation, the new ducts may be run horizontally inside the bedroom floors. These could be connected to the existing ducts at the bottom of the old chase, or new ducts run through the main floor walls. The location of these will be reliant on the existing conformation of the main floor and will likely require modifications to some walls on both floors. Also, removing a portion of the upper floor in the bedroom with the chimney will be needed, but that will have to be patched anyway, after the chimney and duct removal.
Because of this, plans for new floor coverings on the upper floor rooms should be included in the renovation plans. That way, any floor sheathing that is cut for installation of the new ducts can be easily patched. That will also allow for installation of floor level heating and return air registers, which will be a much better location than in the ceilings. The existing ceiling registers should be removed and the attic ducting either abandoned and well sealed, or taken out altogether, to prevent any future issues.
Relocating poorly installed heating ducts and registers, along with a nuisance chimney, is a good plan when upgrading your furnace. It will involve some removal of wall and floor coverings, possibly on both floors of your home, but should be worth the effort. Moving all of these to the warmer areas inside the living space will prevent possible condensation and moisture issues possible with the current duct location.
Ari Marantz is the owner of Trained Eye Home Inspection Ltd. and the past president of the Canadian Association of Home & Property Inspectors — Manitoba (cahpi.mb.ca). Questions can be emailed to the address below. Ari can be reached at 204-291-5358 or check out his website at trainedeye.ca.
trainedeye@iname.com