​

4.6m Wide Tunnel House Construction Guide

Overview

This guide outlines the step-by-step process for constructing a 4.6m wide Tassie Tunnels tunnel house. The construction methods apply to all lengths in the 4.6m range (for example 10.5m, 12m, 15m and longer models), with only the number of hoops, ridge pipe sections and plastic length varying. Designed for Tasmanian conditions, these tunnels prioritise strength, ease of assembly and wind resistance.

 

Parts Supplied

• 35mm galvanised steel hoop sections

• 35mm galvanised ridge pipe

• 32mm galvanised cross supports

• 32mm galvanised end hoop braces

• 32mm galvanised angle braces

• 35mm clamps and connection hardware

• 16mm reinforcing bar ground stakes

• Door frame components

• Door support components

• Wiggle wire channel

• Wiggle wire

• 8.5m wide, 180gsm UV-stabilised greenhouse plastic

• Rope tie-down system

• Brace plates

• 6mm stainless steel shackles

• Tek screws, bolts, washers and nuts

3. Tools Required

• Post driver or sledgehammer

• Cordless drill or impact driver

• Tape measure (minimum 8m)

• String line

• Spirit level

• Ladder

• Pliers

• Marker or chalk

• Hacksaw or angle grinder (for trimming pipe where required)

• Safety glasses

• Work gloves

4. Site Preparation

1. Select a flat, well-drained site.Clear off any cables ,water pipe ect ,Know your site before you attempt to start 

2. Where practical, position the tunnel so the flat ends are not facing the prevailing strong winds. This will help reduce wind loading on the structure.

3. Temporarily place the first corner rod,Measure 4.6m across to establish the opposite side.Eye up the direction you want the tunnel to be.

4. From the first rod run a string line and tape measure, place other end rod at desired length ,pull sting line tight and mark 1.5m spacings.

5. Use two tape measures to measure the across 4.6m and the spacing 1.5m, carry along till all done, run string line to check.

6. Also Measure diagonally from corner to corner until both diagonal measurements are equal. This ensures the tunnel is square.

5. Ground Post Installation

1. Install the first corner stake.

2. Install the second corner stake on the same side of the tunnel, checking measurements as you go.

3. Install the remaining ground stakes along this side, ensuring they are aligned with the string line and spaced at the correct centres for your tunnel kit.

4. Install the corner stakes on the opposite side.

   • Ensure the carabiners are facing the outside of the tunnel.

   • Ensure the welded brackets face the opposite corner of the tunnel.

5. Measure 4.6m across from the first side to position the opposite side.

6. Measure the diagonals and adjust until both measurements are equal to ensure the tunnel is square.

7. Install the remaining ground stakes on the second side using the string line as a guide.

8. Drive each 16mm reinforcing bar ground stake approximately 800mm into the ground.

9. Add one carabina to each anchor plate, and drop over each rod,(corners already done)have them all facing the outside of the tunnel.

6. Construct Hoops

1. Lay out the two straight legs and three bent sections on a flat surface.

2. Arrange the sections in the following order:

 

Straight Leg ─ Bent Section ─ Bent Section ─ Bent Section ─ Straight Leg

 

1. Before joining the hoop together, slide the required 35mm brace bands onto the correct sections as shown in the brace band layout below.

2. Join each section using 200mm long 32mm pipe joiners.

3. Secure each 200mm pipe joiner using two tek screws.

4. Ensure all tek screws face the inside of the tunnel to help protect the plastic cover.

 

7. Install the Hoops

1. Starting at one end of the tunnel, lift the first completed hoop into position and slide both legs over the ground stakes.

2. Continue installing the remaining hoops, ensuring they are fitted in the correct order according to the Brace Band Layouts.

3. Check that each hoop is fully seated on the ground stakes and standing vertically.

8. Install the 3m Cross Supports

1. Starting at one end of the tunnel, install the 3m 32mm cross support onto the first hoop.

2. Secure the cross support to the brace bands using the supplied brace clamps.

3. Leave all bolts slightly loose until every cross support has been installed.

4. Check that all supports are level and tighten off ,make sure the end bolts are facing inwards.

5. Tighten all bolts securely.

9. Ridge Pipe Installation

1. Starting at one end of the tunnel, loosely attach a 32mm cradle (2 supplied)then place the first 2.4m 35mm ridge pipe into the ridge cradle on the end hoop.

2. Secure the ridge pipe to the end hoop using tek screws, tighten off cradle.

3. Position the next 2.4m 35mm ridge pipe and join it to the previous section using a 200mm long 32mm pipe joiner.

4. Secure each join using two tek screws, ensuring both screws face the inside of the tunnel.

5. Check the first hoop is straight with a level,Continue adding 2.4m ridge pipe sections, joining each section with a 200mm long 32mm pipe joiner as you work your way down the tunnel.

6. Secure the ridge pipe to each intermediate hoop using the supplied 35mm cross clamp and bolt and nut only.Check 1.5m spacing with every hoop

7. Do not install tek screws in the cross clamps.

8. Finish by securing the final ridge pipe section into the ridge cradle on the opposite end hoop.

9. Stand back and sight along the ridge pipe to ensure it is straight before fully tightening all clamps and fixings.

10. Install the Angle Braces

1. Install eight 1.65m angle braces, with four at each end of the tunnel.

2. Position the angle braces between:

   • Hoop 1 and Hoop 2

   • Hoop 2 and Hoop 3
     at both ends of the tunnel.

3. Install all angle braces in the same direction, running from the higher brace band to the lower brace band.

4. Secure each angle brace using the supplied clamps, bolts and nuts.

5. Tighten all bolts securely.

6. Install one tek screw through each corner anchor brace clamp to prevent the clamp from rotating.

7. Check that all angle braces are secure and that the tunnel frame is rigid with no movement.

Installer Tip: Leave the angle brace bolts slightly loose until all eight braces have been fitted. Once installed, tighten all bolts and then install the tek screws into the corner anchor brace clamps.Always checking your 1.5m spacing

11. Door Frame Construction 

1. Assemble the door frame to the desired opening size. You can assemble the door here to help you aline the frame.

2. Position the door frame centrally in the end hoop.

3. Install two 35mm × 2.2m door uprights on each side of the door opening.

4. Fit 35mm clamps to the bottom of each door upright.

5. Install 32mm brace clamps to  3m cross support connects to the door uprights.

6. Install one 35mm sliding adjustment pipe between each end corner and the corresponding door upright (two adjustment pipes per door frame).

7. Check that the door frame is square and plumb using a spirit level.

8. Tighten all clamps and bolts securely.

Installer Tip: Leave the sliding adjustment pipes slightly loose until the door frame has been aligned. Once the frame is square and plumb, fully tighten all clamps and bolts.Leave door off till last.

12. Wiggle Wire Channel Installation

1. Install the wiggle wire channel to both end hoops using 2m channel sections.

2. Starting at the top centre of each end hoop, bend the channel around the curve of the hoop.

3. Keep the channel centred on the pipe and secure it using tek screws every 300mm as you work around the hoop.Keep screws as central as possible.

4. Continue installing 2m channel sections until each end hoop is complete.

5. Install wiggle wire channel the full length of the 3m end cross support facing out, keeping it centred and securing it with tek screws every 300mm.

6. Install wiggle wire channel to both door uprights on each end.

7. Check that all joins are neat and there are no sharp edges or protruding screws that could damage the plastic cover.

13. Main Plastic Installation

IMPORTANT: Install the plastic on a calm day with little or no wind.

1. Unroll the 8.5m wide greenhouse plastic alongside the tunnel, taking care not to drag it across sharp objects.

2. Pull the plastic evenly over the tunnel and centre it from side to side.

3. Leave approximately .5m of plastic overhanging each end of the tunnel.

4. Starting at one end, secure the plastic into the wiggle wire channel along the end hoop.

5. Work from the centre of the hoop towards both sides, keeping the plastic straight and wrinkle-free.

6. Move to the opposite end and pull the plastic tight by hand before securing it into the wiggle wire channel.

7. Check that the plastic is centred and evenly tensioned before continuing.

Installer Tip: Pull the plastic as tight as possible before locking it into the wiggle wire. Tight plastic will last longer, flap less in the wind, and give a better finished appearance.Add a small section of wire first then do the same at the other end to make sure its all right.

14. Rope Tie-Down Installation

1. The rope tie-down system can be installed either after the main plastic has been fitted or after the end plastic has been completed.

2. Starting at one end of the tunnel, tie the rope securely to the first carabiner.

3. Run the rope over the tunnel to the second carabiner, then back over the tunnel to the third carabiner.

4. Continue this crossover pattern for the full length of the tunnel.

5. Pull each rope section tight by hand before tying it off.

6. Tie each section individually using a slip knot. Do not use one continuous rope for the full length of the tunnel.

7. Repeat the same process from the opposite side of the tunnel.

15. End Plastic Installation

1. Cut the end plastic to size, leaving enough excess material for tensioning and trimming.

2. Position the plastic over the end hoop, ensuring it is centred.

3. Starting at the top centre of the end hoop, install the wiggle wire to secure the plastic.

4. Work evenly down both sides of the hoop, alternating from left to right to keep the plastic straight and evenly tensioned.

5. Pull the plastic tight as you work around the hoop, removing any wrinkles.

6. Finish by securing the plastic to the 3m end cross support using wiggle wire.

7. Trim any excess plastic using a sharp knife or scissors.Cut channel and wire as you need shorter lengths .

Installer Tip: A light fold down the centre of the plastic can be used as a guide to help keep the end sheet centred on the tunnel.

17. Door Assembly & Installation

1. Assemble the door frame to suit the finished door opening.

2. Check the door frame is square by measuring diagonally from corner to corner. Adjust as required before tightening all fixings.

3. Install wiggle wire channel around the perimeter of the door frame.

4. Keep the wiggle wire channel centred on the pipe and secure it using tek screws every 300mm.

5. Lay the door on a clean, flat surface and position the plastic over the frame.

6. Starting at the top centre, secure the plastic into the wiggle wire channel.

7. Work evenly around the door frame, keeping the plastic tight and wrinkle-free.

8. Trim any excess plastic from around the door.

9. Hang the completed door using the supplied hinges.

10. Secure each hinge using the supplied tek screws (approximately three screws per hinge leaf, or as required).

11. Check that the door opens and closes freely and adjust if required.

12. ​