How to build a Greenhouse
ARTICLE CONTENTS - User Comments/Photos
Description
STEP 1. The greenhouse base
STEP 2. The side walls
STEP 3. The roof frames
STEP 4. The end walls
STEP 5. The windows
STEP 6. The doors
STEP 7. The greenhouse cover
Materials and quantities
Description
This greenhouse, approx 8ft wide x approx 10ft long , is lightweight, portable (can be fixed more permanently if required), inexpensive and easy to construct. The cover is clear UV-resistant polythene film. This greenhouse is ideal for those areas with a tendency to have just enough winter frosts to be annoying.

Update note: There is now a new version of this greenhouse project online.
Taking feedback into consideration, the new version includes a 2"x4" (100mm x 50mm) frame, a wider door (wheelbarrow size), a bit more inside height,
and...
it is print friendly.
Click here to go to the
new updated version
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Lumber and lumber size.
The lumber used in this project is 'sawn' also called rough sawn or rough lumber. That means that the lumber has not been dressed (surfaced, planed or gauged). If you prefer to used dressed lumber, then the sizes (width and thickness) of the lumber will differ. For example; a piece of 2"x 3" lumber when dressed will
end up being approximately 1 1/2" x 2 1/2". If you use dressed lumber some measurement adjustments will need to be made to compensate for the difference in lumber size.

Where to place the greenhouse.
Pick a site likely to get the winter sun. The site should not be in an area likely to be boggy and should be level or in a place that is easy to make level. If the site is below a hill or slope, then it might be necessary to put in a drain (open, tile or scoria) to re-direct any water flow away from the greenhouse site.
STEP 1. The greenhouse base


Once the level greenhouse site has been determined, make the base which is constructed out of 4"x4" treated, or natural decay-resistant, sawn lumber.

Make a rectangle 94-1/2" x 118" as shown in the drawing above. Fix the lumber together in the corners by using galvanized nails and nail plates.

Check that the two diagonal measurements are equal. If they are not, make any necessary adjustments. When the diagonals are equal, then the base is square.

Check that the base is level, either by using a spirit level and a straight edge or by using the water level method

Secure the base in place by driving stakes into the ground around the perimeter.
Nail the stakes to the base and cut flush any stakes protruding higher than the base lumber.

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STEP 2. The side walls

Construct all the framing out of 2"x3" treated, or natural decay-resistant, sawn lumber.


On a flat piece of ground, make two side wall frames as per dimensions shown in the drawing above.

Make the diagonal measurements equal (in the same way as with the base in Step 1) and when the walls are square, cut and fix the bracing members in place. (See above drawing.)

Stand the two side walls upright and temporarily prop up in place on top of the base. Fix the bottom plate of the side walls to the base boards with galvanized nails.

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STEP 3. The roof frames


Cut all roof frame pieces as per dimensions shown above. Use 2"x3" treated, or natural decay-resistant, sawn lumber.

In all, cut 5 rafters @ 74-3/4", 5 rafters @ 51-1/2" and 5 uprights @ 12-7/8" all with end angle cuts as shown in drawing.

Also cut five triangular gussets 19-5/8" x 19-5/8" x 19-5/8" from a sheet of 3/8" treated plywood.

On a flat piece of ground, make up the five roof frames to the pattern and dimensions as shown in above drawing. Ensure the two furthest points are 94-1/2" apart and then nail the triangular gussets in place with galvanized flathead nails spaced about 2" apart, one gusset to each roof frame.

Lift the 5 roof frames in place on top of the side walls, one roof frame to each end of the side walls and the other three spaced evenly in between. Fix the roof frames to the side wall top plate with galvanized nails.

Temporarily prop the two end roof frames plumb (vertical).

Nail the fascia board (1x6) to the top of the roof frames as shown in the drawing below, making sure all the roof frames are vertical and parallel with each other.

Fix the window support plate (2"x3") in place under the roof frame apex and behind the fascia board. (See drawing below.)

Brace the roof on the side that has no windows. Nail metal strapping from the apex of both end roof frames down to the middle of the side wall top plate.

Continue........
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