Home Addition-The Nuts and Bolts of Adding On

Home addition

Adding on to a home is complex undertaking and with all the details to be worked out it's easy to overlook anything that isn't tied to nails and wood. Even in a basement remodel the space has to be tied to the amenities of the main home: plumbing, HVAC, electrical, etc. And these important functions have to be addressed before the first tool comes off the belt.

External Consideration


In every addition that includes a bathroom a licensed plumber will have to be involved. Even the handiest do-it-yourselfer can't create an expensive problem if the water, sewer and drainage are not planned.

Sewer: For example, if the addition includes a basement and you want a bathroom in the basement the plumbing considerations have to be addressed long before the cement truck gets there. Sewer pipes will have to be hooked up for the toilet and shower before the floor is made. Many an experienced contractor has had to jackhammer part of a basement floor because the proper subterranean piping was missed.

Water Supply: In addition, water is needed and if the source is in the main part of the home this will be an easy undertaking for the plumber. However, if the addition is over top of the water supply coming from the street then the pipe will have to be carefully excavated before the full basement is dug. Then the plumber (along with the building inspector) will have to either move the input for the water supply or include it in the addition.

Home Fuel

Gas Line: Just like the water pipe needs to be found and moved, if the house is heated by natural gas, so does the gas line. A gas company representative will have to over your plans and then have a crew unearth the pipe and move it. If a new furnace is going into the expansion then the pipe will be shortened or lengthened later on. For the present they will probably add a splice to get it out of the way of the construction. This would be the same with a large propane tank, if the lines were underground.

Oil Tank: In many parts of the country oil is still a primary heat source. If the tank is in an external spot, and in the way of the renovation, then it will have to be moved under the eyes of a certified plumbing and heating professional. Even if moving an oil tank looks easy the tank may not be in great shape and your attempts to move it might cause a large spill. If that happens then your government agency may require that you excavate a large area around the spill so that it doesn't get into the ground water. And this will be an unwanted expense as well as a sum that you insurance company will not cover because the work was not carried out by a professional.


Many areas have underground power, telephone and cable to their homes. As with the gas and water, the power company will have to be notified before digging. Hitting an underground power line might not only take your neighbourhood off the power grid it might cause injury or death.

Interior Considerations


Even if your renovation is a second story you will have to look at the heating requirements. Because there are next to no areas of the country that do not get cold in the winter. If it is duct heating then the HVAC professionals will be subcontracted by the contractor (or you). Depending on the size of the addition the heating contractor will compute the amount of heat needed and see if you present system can handle the load. Usually, unless you are adding a terrific amount of space, the newer furnaces can handle excess capacity. But if the unit is older then it might make sense to install a new one. New means a warranty and also has an advantage in energy savings. However, if you purchased you system just a few years ago then get another opinion before changing it out. As well, a heat pump may need a larger compressor to handle the added space.

Another consideration in central heating is where to place the new ductwork. If you are using electric heating then this is an electrical matter and electric heat can be applied in many disguises: in-floor, baseboard, radiant ceiling, electric thermal storage units.


Most homes newer than 30 years have 200-amp service but this may not be enough for your addition. Depending on how large you go the electrical requirements will be increased dramatically. This will be a huge factor of you are considering electric heat.

The contractor's architect will automatically have this factored into the project but if you are doing most of the building yourself you will need an electrician to help you with your plans.


If you are planning for radiant in-floor heat or baseboard water heating then your plumbing requirements will also include your heating. This is in addition to you regular requirements if you were planning to put in a kitchen or bathroom in the new area. Hot water heating can be separate from the regular plumbing: an electric on-demand boiler or a separate system with a small electric water heater. However, if you put on a living room or another bedroom the regular water, hot water and drains would not be required.

Posted by: TrustedPros
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