STEP-BY-STEP POLE STRUCTURE
Pole-building is one of the oldest and most
basic systems of construction. The method demands minimal preparation of the
site, even on sloping ground, and structures are quick and easy to erect.
Although basic carpentry skills (including experience with power tools and a
knowledge of
fixing and fastening techniques) will be a help, even an unskilled
person can tackle a simple pole structure successfully.
The versatility of this building method creates
many design possibilities, and it may be used for a structure of any size. The
one discussed here is only 7.5 m2 in area, and has a covered deck 1 m wide and
a height of 2 m. This structure is extremely versatile and can be adapted to
form a variety of structures, from a potting shed or tool shed to a children’s
playhouse.
MATERIALS
Poles or sawn and planed posts may be used as
vertical supports. These are embedded in the ground and attached to horizontal timbers which form a
framework for the wall cladding.
In order to accommodate doors and windows, it is
necessary to construct a stud framework to brace the walls. Ordinary,
factory-assembled frames are easily installed; however the minimal dimensions
of some structures, such as the one shown here, may demand that a
smaller-than-usual door is used. The simplest
1.
Mark the layout of the building on the ground using pegs and string. This shed
measures 2.5 m x 3 m. Use the 3:4:5 method to ensure that all corners are at
right angles and the building is absolutely square.
Solution is to construct a frame on site using
wooden laths.
If relatively weak softwood decking slats are
used, these should be quite thick (in this case 110 mm x 35 mm). If a tougher,
more resistant wood is used, or if the bearers are closer together, thinner
slats can be used.
Although standard bargeboard and fascias may be
used to finish the little building, a less expensive and much prettier option
is a plywood trim.
2. If
there is a deck, you will need to indicate where this will be located. To do
this, string a line 1m from the front 2.5m mark, using a builder’s square for
accuracy. To double-check that the layout is square, measure all the diagonals.
3. Cut
as much wood to size as possible. These four bearers are 3m long, and the five
joists which support the floorboards, 2.5m long. If necessary, trim the wood
now, using a combination or try square to mark the cutting line.
4. Although you can use a hand saw, it will be
quicker, and the cut will be more accurate, if you use an electric circular
saw. As neither the joists nor the bearers will be visible, it will not be
necessary to plane the cut ends of the wood.
5. The
upright posts will have to be firmly anchored in the ground, preferably in a
concrete footing. A good way to prevent any vertical wind lift is to drill a
hole and insert a metal rod through the timber a few centimetres from the base.
6. The
holes for the 14 footings should be at least 500 mm x 500 mm x 500 mm in size.
Dig them all, but only insert the four outside posts, bracing them with battens
and bricks to ensure that they are as vertical as possible.
7.
Although many people concrete the posts in at this stage, it is easier to keep
the structure square and plumb if you start by securing all bearers, joists and
uprights. Position the two outside bearers first, using blocks of wood to level
them.
8. Use
the correct drill bit to bore through the end of each bearer and the base of
each of the four upright posts. You will need two suitable coach screws at each
point to fasten the timber securely. Tighten the screws with a spanner.
9. It
is vital that the outside bearers are affixed at exactly the same height, or
your finished floor will be uneven. Use a straight-edge with a spirit level
placed over it to check. If the ground slopes, one end of the bearers will be
off the ground.
10. Now
you can position the first joist at the back of the building. Check that it is
level and pre-drill holes as before. Use the same length coach screws to secure
the joist to the two posts. Then attach the central and front joists of the
structure.
11.
The next step is to position the remaining upright posts (see step 12) and two
inner bearers. This way you will not have to brace the posts. Once these are
securely fixed, position the last two joists as shown on the plan and
skew-nail to the bearers.
12.
The two longest upright posts should be positioned opposite one another, to
coincide with the apex of the roof. The four shorter posts should be placed at
810 mm centres at the front of the building, to support the railing and
verandah roof.
13.
Remove the bracing, but before you go any further, double-check the upper plane
of the joists and bearers. Do this at numerous points to make absolutely
certain your workmanship is straight and level. It is easier to rectify errors
now than later.
14. If
you have used sawn (rather than planed) timber, you may have to use a rasp or
file to trim, flatten or even out sections of some of the pieces. You are
unlikely to need a plane unless the wood is badly bowed; there is no need to
sand the wood.
15.
Now you can concrete the posts in place. Use a 1:4:4 mixture of cement, sand
and stone and place it in the holes with a spade. If all the posts were
vertical when they were bolted, the building will be square. Allow the concrete
to set overnight.
16.
The first decking slat will have to be cut and notched to accommodate the
posts. Position it on the bearers, and then draw a line where you are going to
cut out. Accuracy is extremely important, so is best to use a combination
square.
17.
The best way to notch timber is with a handsaw and chisel. This gives you
better control than with a power saw. Work on a stable surface, like a portable
workbench, and use a crosscut saw which is designed to cut across the grain.
18.
Although you can use a saw or a chisel to finish cutting the end joint, you
will have to use a chisel to cut the back of the notches which will accommodate
the two inner posts. Use a hammer to drive the chisel blade gradually into the
wood.
19.
String a line along one end of the deck as a guide, then secure the slats with
anodised nails. Use a block of wood, planed to the width of the gap you wish to
leave between the slats, as a spacer. Trim the other end of the decking as in
steps 22 and 23.
20.
Moving on to the inside of the structure, cut the tongue off the first
floorboard and nail the board in place with two oval nails at each of the
joists. Continue laying the flooring, slotting the tongue of each board into
the groove of each previous one.
21.
Line up the ends of all the boards at the front of the building. You will need
to notch some of these ends to accommodate the posts, and to trim those which
lie at the point where the door is to be hung.
22.
Now you can trim the boards at the back of the building. These must line up
with the edge of both the bearer and the upright posts. The best way to ensure
that the cutting line is straight is to make use of a chalk line, snapping it
between two posts.
23.
You can use either a handsaw or a power tool to cut the boards to size.
Although you could use a circular saw, it is easier to obtain a really flush
cut by using a jigsaw. Otherwise, use a crosscut saw, and follow the line
marked previously.
24.
Before you affix the cladding, assemble the roof structure. Use a water level
to determine the correct height of all the upright posts. The height of the
middle posts will be determined by the required pitch; these are 200 mm higher.
25.
Once you have measured and marked all the upright posts, you can cut the excess
ends off with a cross-cut saw; it is too awkward to use a power saw. Note that
the two higher posts should be cut at a slight angle to support the rafters.
26.
Before securing the beams, cut a notch at the top of each post, in a dimension
which will support the rafters. Then, using coach screws, fasten the beams to
the uprights, so that the upper surface of each is flush with the newly cut
wood.
27. To
prevent the two central beams below the apex of the roof from bowing and
bending, sandwich a block of wood between them at the centre, and secure with a
hexagonal bolt and washer, using a spanner and ratchet to fasten it.
28.
You will need eight lengths of timber for the rafters which will have to be cut
at a slight angle to ensure that they join properly at the apex. Position a
shorter length on the cut-out posts and use a combination square to determine
the angle.
29.
Mark the same angle for all the rafters, checking before cutting the ends.
Drill through the rafter and post, then fasten the wood to form a half-lap
joint, using a smaller sized coach screw. Repeat at both ends of each rafter.
30.
The rafters are best joined at the apex with nail plates (timber connectors),
available in various sizes. Working on the ground, simply hammer a plate on
each side of the wood over the join. Alternatively you can make a plywood
gusset.
31.
Once all the rafters have been positioned and secured, string a line along the
apex of the roof. Use this as a guide when measuring and marking where the
purlins should be affixed. Remember to leave a space at the apex for the
capping.
32.
Now attach the purlins to the rafters with 75 mm long anodised nails. Use the
marks made in step 31 as well as the string line to ensure they are nailed on
absolutely straight. If the purlins are crooked, the roofing nails will not be
neat.
33.
Before you lay the roof sheeting, nail the cladding to the posts.
This splayed lapboard is designed to create a
weatherproof wall. Use two nails at each post and check your spirit level
periodically to see that the boards are horizontal.
34.
While the cladding is nailed across the posts on three walls, the front wall
incorporates a door and a window. To brace these openings, it is necessary to
build a stud framework. Secure timber with anodised nails.
35.
Studs around the window are nailed to the upright posts, to create an opening
exactly the same size as the frame. Although any type of window may be fitted,
a PVC frame is one of the easiest to work with as it simply slots into
position.
36.
Before the window can be glazed, the frame is screwed to the studs. The inner
PVC frame is removed and holes drilled through the frame and into the wood.
Countersunk brass screws are used to ensure the frame is flush when it is
reassembled.
37.
When you reach roof height, it will be necessary to notch the cladding around
the purlins and cut it to the angle of the rafters. Use a spirit level as a
straightedge to mark the cutting line and then saw the timber with a cross-cut
saw.
38.
Buy longer lengths of sheeting than required and cut to size. The flexible corrugated
sheeting used here is made from organic fibre, which can be cut with an angle
grinder or well-oiled handsaw. Mark a line with a chalk line and cut a straight
edge.
39.
String lines along all edges of the roof to help you keep the roof sheeting straight.
Note that the sheeting must overlap at the joins to ensure that it is
waterproof. Align the sheets carefully so that the corrugations overlap
exactly.
40.
Although it is usually necessary to pre-drill holes for roofing nails, this is
not necessary for organic-fibre sheeting as long as you hammer gently. Knock in
the nails, using a spirit level and lines to gauge the position of the
underlying purlins.
41.
The ends of the rafters should line up neatly with the ends of the roof
sheeting. Use a carpenter’s square to mark this point accurately. Then use a
crosscut saw to cut all the excess pieces of timber at the front and back of
the shed.
42.
The purlins must also be cut so that they are flush with the roof sheeting on
both sides. Bargeboard, or in this case a decorative trim, can then be nailed
to the ends of the timber. Once again it is best to use a handsaw to cut the
wood.
43.
Now affix the capping to close the gap between the sheets which cover the two
halves of the shed. Capping is supplied in standard lengths and must be
overlapped in the same way as the sheeting. Secure with roofing nails along the
purlins.
44.
Most of the work has been done, and now you can make the railing around the
deck. First affix a supporting strut to the shed at the corners of the deck,
opposite the two outer posts. Then mark cutting lines on all your crosspieces.
45. As
the crosspieces below the rails are angled, the ends of each piece must be cut
to form a V at both top and bottom. Use a carpenter’s square to draw a straight
line down one side of each piece to help you cut in a straight line.
46.
Preferably clamp the wood to a portable workbench and use a tenon saw to angle
the corners. It is best to cut all the wood before you start assembling the
railing. It is also a good idea to check that you have cut the correct angle.
47.
Now cut a housing in the centre of each crosspiece so they slot together
neatly. It will be slightly angled, depending on the length of the diagonals
and where they meet. Mark this position and make a series of cuts halfway
through the wood.
48.
Chisel out the excess wood from the notch. If the cuts made previously are
accurate, you will find that you can simply trim the wood at the base line.
Otherwise you will need to pare away the remainder with the chisel blade.
49.
The two diagonals should now slot together neatly. There is no need to affix
them at this point, although you can glue them if you wish. Once the
crosspieces have been secured to the posts and support struts, the railing will
be quite sturdy.
50.
You can nail or screw the crosspieces into place, but to avoid splitting the
wood, it is best to pre-drill the holes. Use the appropriate drill bit and
angle each hole. The upper sections are affixed to the posts and lower pieces
to the decking.
51. If
you are using nails, use ones that are anodised and will not rust. Make sure
you hammer them in so that the tops are flush with the wood. It is also a good
idea to countersink them with a punch and fill the holes with wood filler.
52.
Now fit the top railings over the criss-cross by skew-nailing them to the
upright posts on each side. A drilled pilot hole will help to prevent the
timber from splitting. Make use of an orbital sander to smooth the edges and
round them off neatly.
53.
Nail the laths to the inside of the doorway to form a narrow frame along the
top and sides, using 50 mm long nails. Then hang the door so that it opens
outwards, above the upper surface of the deck. Fit the lock and the handles.
54.
The quadrant can now be nailed to the four outside corners of the building
using suitable nails. This finishes off the corners neatly. You could also use
square lengths of wood or PVC capping for a decorative edge if you wish.
55.
Mark the design for your trim on the plywood and cut it out with a jigsaw. Any
holes can be made by drilling, using a flat drill bit. Attach it at the front
and sides of the structure with 50 mm nails. Also cut out closures for the
capping ends from the plywood.
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