There are at least three types of foundation that may be used with any of the cottages shown in this book. These are: a concrete slab on grade; a full foundation wall (or basement) around the outside perimeter of the building; and a pier type of foundation. All the drawings in the book show pier foundations, because they are usually the cheapest to build and the easiest for the amateur craftsman to construct.

 

 

Concrete Slabs on Ground

If you have a level piece of property on which to build, you may want to use a concrete slab. It is fairly simple to make. After you have selected the cottage or camp you wish to build, refer to the foundation plan that is shown with it. Get the over-all dimensions firmly in mind.

On your site clear away the brush and  lay out the lines of the  building  with strings and batter boards as shown below. The next step is to dig a trench about  12 inches deep and 12 inches wide around the perimeter of the building. If you hit some large rode, leave it. Taper the inside edge of the trench as shown. By cutting the outside edge of the trench square, you can use it as part of the form for the beam edge of your slab.

While you're trying to get the crimp out of your back, have your wife call the local supply yard and have them send you enough gravel or crushed rock to lay a 6-inch bed under the slab. The following table tells you how to figure how much grave! or crushed rock you will need.

At this point, while you are waiting for the delivery of the material, you will want to get all the rough plumbing in place. This means that all the pipes which will be permanently buried in the slab should be put in place, connected, and tested. See page 174 for illustration of pipes which have to go into the slab.

When the rock or gravel has been delivered, borrow the neighbors' wheelbarrow and start spreading it. The finished bed, in cross section, will look like the picture at the side. Don't stop now, you've only begun.

Get enough 15-pound roofing felt to cover the slab area. Cover the gravel area with this, lapping the edges about 3 inches. You're doing this, I might add, to keep the ground dampness from coming up into your finished slab.

Around the outer edges of your cottage build a form as shown in the picture at the side. I assume that you didn't knock the walls of your trench in; if you did, be sure to clean them out again. You are now ready to lay the reinforcing down. The usual procedure is to use wire mesh weighing 40 pounds per 100 square feet. If you can't get it, the best substitute that I have seen is heavy turkey wire (welded type). Roll out the mesh. Put some small rocks under it so that when the concrete is poured, the mesh will be in the slab. Along the bottom of the trench use two %-inch reinforcing bars. You're actually building a concrete beam around the perimeter of the building.

You are now ready for the big pour. By this time you will probably be willing to call for transit mix. When you ask for this prepared mix, tell them you want the kind that reaches a minimum compressive strength of 2,000 pounds per square inch in 28 days. If you are going to mix your own concrete, use I part portland cement, 2 parts sand, 4 parts coarse aggregate, and enough water to make it sloppy. The actual water content should not exceed 7|/2 gallons per bag of cement. The table will help you to figure how much you will need. The thickness of the concrete slab should be a minimum of 3 inches. After you have the framing up, you will want to add one more inch of smooth concrete for your final finish (I part cement, 3 parts sand). You can also add color to this batch if you don't like the natural gray of the concrete.

There you are. Except that you should also put some 6-inch stove bolts along the outer edge of the slab, about 8 feet on center, starting roughly I foot from the corner, to fasten your sill. If you are going to use the cottage year-round and are building in the northern states, insulate the outside perimeter with Fiberglas boards.

If you use the slab described, be sure that the soil is porous. Heavy clay or stiff soil will require the building of foundation walls to the frost line to prevent heaving.

Full

This type of foundation sounds easier to build than a slab. The only catch is that you'll probably have to do a lot more digging. This is especially true if you live in the northern part of our country. A little north of New York City we usually extend our foundations down 4 feet. You'll want to find out how far down the wall and footings should go; the local building inspector or mason can tell you. With this information in mind, lay out the outlines of the building as described above and start digging. The walls that form your foundation will probably be built of 8-inch concrete block. This wall should rest on a footing. The illustration at the side shows one way such a footing can be made.

Like the beam described above, the dirt may be cut square and be used as the form. The footing should be at least 6 inches thick and project 2 or not more than 3 inches beyond the thickness of the wall.

This concrete footing is made of I part portland cement, 3 parts sand, 5 parts coarse aggregate, or a transit mix that will have a minimum compressive strength of 1,500 pounds per square inch in 28 days.

If you are making the walls of block, the mortar you should use is composed of I part portland cement, 3 parts sand by volume, and lime not exceeding 25 per cent of the cement by volume. Stagger the blocks so that the joints of the second row of blocks fall over the mid-sections of the blocks below. Use closed-end blocks for corners. Moistening the blocks before laying them will help hold the mortar. Pour concrete into the top row of blocks and insert 6-inch bolts, 8 feet on center, for the sill.

Foundation Piers

This is the type of construction you will probably use. It is the quickest way to get your summer home under way. Each cottage unit in this book has a pier plan which you should follow.

There are several rules to remember about piers. They can be built of block (8 by 8 by 16 inches) or of solid concrete. Piers require foundation footings just as walls do. Take the advice of the local building inspector on the depth they should extend below grade. You'll want to have the footing below the local frost line. The illustration at the side shows the usual arrangement for the footings. Poured concrete piers should be 10 by 10 inches if square or 12 inches in diameter if round. I have seen a posthole digger used to make the hole for a round pier. It worked. The only trouble is that the center of the pier is the used part and some portion of the pier will project beyond the building line. The proper mix is the same as for footings mentioned above. The maximum height above grade that you should build a pier is four times its least dimension. If the pier on the low side of your camp is 6 feet, the pier size should be increased to 18 inches square. The forms for solid concrete piers may be made from any old lumber. The illustrations at the side should show you how.

Take your choice of these three ways to build your foundation. Some may ask why I haven't mentioned wood post construction. I'm not convinced that they are worth using except above grade. If you must use wood, be sure that you get pressure-treated posts. Dipped or painted ends are little protection.

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