From your question, it sounds like you are planning to caulk gaps where the windowsmeet the sash and the sill and you will need to remove the caulk when you open thewindows.
- This is a somewhat unconventional solution.
- In our climate (I live in LosAngeles) it could be 80 degrees in January when you might want to open the windowsduring the day and then close them at night.
Repair the windows
A more conventional approach would be to have the windows repaired. If you are theowner of the cottage it would be a good investment; and if not you might suggest it toyour landlord.
- Q-Lon weatherseals with a polyethylene cladding can be installed to thesash and frame of the windows and doors to create a tight seal.
- A kerf or groove is cutinto the wood and a bulb like weather strip inserted into the groove.
- The seals are notpaintable but come in a number of colors. These can be easily removed for painting.
- Thepolyethylene cladding will not release any toxic fumes in its finished state.
- A professionalwould need to install this. A window and door distributor in Los Angeles recommendedKnight Construction (at 1-818-894-2362) to do the work. You could also ask themanufacturer for other installers.
Removable sealant is a less expensive alternative
Should that be too expensive, you could install a removable sealant as you discussed.
- Latex and Acrylic caulks can be removed by simply pulling them up or cutting them outwith a utility knife. These caulks are typically for the interior.
- OSI's Green Series Draftand Acoustical Sound Sealant by Henkel for interior use contains no formaldehydes.
- Ipersonally have not experimented with trying to remove it so if you should chose thisroute, first test it.
Other drafty leaks could be the cause of heat loss
With that said, there are many areas other than the windows that could be the reason thatyour house doesn't retain heat. According to the U.S. Department of Energy,
"caulkingdrafty areas of a building can cut energy costs 10%; furthermore, about 50% of theaverage fuel bill is the result of heat loss from air infiltration. The energy efficiency ofour houses can be vastly improved with the low cost method of caulking the drafty leaksof your house."
If you decide to caulk exterior areas then a brand that I would recommend is SafeCoat'sCaulking Compound. Theirwebsite states that
"It is a non-toxic, water-based, elastic emulsion type caulkingcompound designed to replace oil caulk and putty for windows, cracks and generalmaintenance work. It will not dry out or crack and does not release any solvents."
Itcleans up with warm water (as does OSI's). You might experiment with this one as wellto see if this is easy to remove. For both of these products, I suggest that you read theTechnical Data on the manufacturer's website for installation instructions. Below I havelisted some information and a brief background on Sealants and Caulks.
Tips for sealing/caulking
Things to consider when sealing/caulking your home:
- Caulks and sealants are usually applied in the same manner, with a caulking gun. Youwill also need a utility knife.
- Clean surfaces so that the caulk will bond properly. Brush or vacuum joints.Adhesion failure is a common reason that joints fail.
- Shape the caulking bead with your finger so that it has a concave shape. This willgive the maximum surface area for adhesion with the center thinner and moreflexible when there is movement in the joints.
- As the building will be more water tight, take care not to trap water in the wall.
- When caulking the exterior, do not to caulk the underside of window and doortrim or clapboard siding. This will allow water that gets in, to get out.
- For gaps deeper than 1/2" first insert a flexible backer rod (foam cording availableat most hardware stores). Then fill to the surface with the caulk preventingcracking. Some products allow a max of 1/4 ", so review the specific technical data.
- Don't rely on caulk where there is shoddy workmanship. Trim and clapboardjoints should be tightly joined.Use a paintable caulk, for areas that are visible.
- In selecting an interior sealant or caulk chose a low- VOC product.
- Seal and insulate the foundation walls of unventilated crawl space.
- It the attic is not properly insulated then your sealing the cracks will not be thateffective. The attic is the easiest place to insulate if you have a crawl space.
About Sealants and Caulks
The terms "caulk" and "sealant" are often used interchangeably, as they serve thesame purpose; filling the gaps between building materials to minimize water and airintrusion.
- "Caulk" was a term first used for a material that seals the space between theboards in boat building; whereas "sealant" was a term that originated in home building.
- Some manufacturers today use the term caulk as an all-purpose term and sealant todescribe their high-performance products.
- Other manufacturers use the term "caulk" formaterials which are more rigid when dry and are used in areas where there is minimalexpansion & contraction. "Sealant" then refers to a more flexible material.
In the past sealants and caulks were either pitch; a material made from plants as pinepitch, or bitumen; a petroleum-derived material. With the development of syntheticpolymers in the 1930's there is now an abundance of manmade rubber-like caulks andsealants. The polymerization process chemically links small molecules to make largermolecules, with the resultant molecules retaining properties similar to the originalmolecules.
Viscosity and elasticity
Two material properties to consider in the selection of a sealant or caulk are viscosityand its elasticity.
- Viscosity describes a fluid's internal resistance to flow and is ameasure of fluid's friction. (Wikipedia) A material with a high viscosity has little to noflow with water considered to have a very low viscosity.
- Elasticity or stretchiness allowsthe material to return to its original shape after the external forces that have caused thechange have been removed. In the case of caulks or sealants the external force may betemperature, or load, such as wind or weight. (Wikipedia)
Five types of sealants and caulks
For residential installations there are five basic types of sealants and caulks:
- Silicone; and
- Polyurethane (and their hybrid types).
Butyl isa polymerized synthetic rubber (polyisobutylene) that chemically resemblespolypropylene, is a viscoelastic material, with good adhesion and is weather resistant andimpermeable. On the negative side, it is stringy like gum and has a low elasticity. Also, itis difficult to get a good quality joint as it has an unattractive tarlike appearance.
- Main uses: Repairing aluminum gutters; caulking aluminum flashing; fillingcracks in asphalt; sealing siding around doors and windows. Good for belowgrade sealing.
- Cleanup: Mineral spirits or lacquer thinner.
Latex is a viscous material made up of the polymerized microparticles in an aqueousmedium. It is applied as a liquid and is typically water-based making it easy to work with.Latex has the least ability to stretch (7% to 10% elasticity) and works best for interiorapplications where little movement is expected.
Acrylic is a family of synthetic resins that are clear, water-soluble and easy to work with.It can be painted and so can touched-up and is goof for filling small gaps. Acrylics have alimited elasticity making them susceptible to cracking w/temperature change and dryingout over time. Siliconized Acrylic caulk (Elastomeric) is a high-performance acrylic, w/greater elasticity and a market favorite.
- Main uses: Utility caulking for nearly all interior and some exterior sealing.
- Removal: Can be removed by simply pulling up or cutting it with a utility knifeand then pulling.
- Cleanup: Water.
- Life span: 5-10 years depending on environmental exposure and buildingmovement.
Silicone is a polymer formulated from silicone oils that can be combined so they willharden at room temperature. The hardening process releases an acetic acid as a by-product, which is an organic compound; the main component in vinegar other thanwater. Although it has a strong odor it is not toxic. It is non-porous and watertight evenw/temperature fluctuations. Silicones are extremely rubbery with 50% elasticity. Theyadhere to non-porous surface but have poor adhesion to materials such as wood. They aredifficult to apply and can't be painted.
- Main uses: Sealing around tubs, shower and sinks; caulking exterior trim; gutterrepair; sealing or caulking against aluminum, glass and other nonporous materials.
- Cleanup: Mineral spirits.
Polyurethane, a polymer of a glycol with an isocyanate, is preferred for outdoorapplications. Polyurethane works well for filling indoor gaps in floorboards as it can takethe high-traffic stresses of floors, though it is not necessary for other indoor applications.The material is hard to control and takes time to set up in situations where an acryliclatex would be perfectly suitable.
Polyurethane has a tremendous bonding ability and soit can be used as an adhesive in some cases. Its removal can be difficult and it usuallyinvolves cutting out or sanding. It can be painted. Polyurethanes are solvent-based and ispotentially hazardous to your health. Cleaning up requires solvent or paint thinner. Userubber gloves and a respirator when applying it.
- Main uses: Sealing control joints in concrete; repairing cracked masonry; exteriorcaulking around windows and doors; repairing cracked vinyl siding; bridging gapsbetween porous and nonporous materials.
- Cleanup: Mineral spirits.
- Life Span: 10 – 20 years
Latex Acrylic Hybrids for enhanced performance.Acrylic Latex Hybrids with Butyl for greater strength.Silconized Acrylic Hybrids offer greater elasticity and a paint-friendly surface foran indoor setting where flexibility is critical.