How To Dismantle a Greenhouse

old greenhouse to dismantle

DISCLAIMER: This information is meant as advice only and intended for those with some experience in DIY and/or construction. We cannot be held liable for injuries sustained while dismantling a structure. All greenhouses are different and present their own difficulties and peculiarities when it comes to assembly and dismantling. Glass is dangerous, and used glass can be more so. Framing materials, such as steel, aluminium and wood, can also be dangerous, as can nails, screws and other fasteners. If you are not confident that you can do this job, please refer it to someone who is, to either assist you or to take over the job entirely. In short, please stay safe and only attempt this if you are confident you can complete the job safely.

Getting Ready / Intro

Taking a structure apart can seem easier than putting one up, but it does sometimes present challenges. One bonus, however, is that there are fewer tools needed to take a greenhouse apart than are needed to put one up.

Basic tools needed include a 10 or 11mm spanner (open-ended); a long, thin-bladed screwdriver; a container for removed fasteners (a bucket or trug works best); a short step-ladder or portable steps; a pair of gloves; and some form of eye protection, such as a plastic facemask or safety glasses.

Work Top Down

As a general rule, work from the top down. Begin by taking all of the glass out of the roof portion of the building. Having a helper around really is essential at this stage, as is additional care, as this is the most likely time you will drop a pane of glass, and the time when it could potentially do the most damage, as it would fall from the greatest height. Use care.

Then proceed to take the glass out of the side walls if possible, before moving on to the frame.

Rebuilding? Take Note

If you plan to rebuild the greenhouse in a different location, it is handy to keep the frame intact in sections. Each slope of the roof, for example, might be kept as one piece. This requires a vehicle with a large enough roof rack, or a van with large enough dimensions to fit the sections in. The advantage of this, of course, is that you take less of the structure apart and have less to set up again once you reach your new destination. It does require a little more strength when moving it, and there is an increased chance of bending it while moving it, so there are risks as well, despite the added convenience. Doing it this way, you are also less likely to get confused when trying to put it back together.

Clip Removal

When removing the clips, good technique and the right tool will save you from a lot of frustration and will make the job a lot quicker. There are various kinds of clips, but most of them are similar enough to employ the same removal technique.

Insert the screwdriver blade under the clip and gently lever it, a little at a time to prevent damage. Keep a finger over the clip as you remove it to prevent it from flying up to hit you or be lost in the lawn.

Take Care With Slippy Glass

It is worth mentioning that the glass might be slimy, even if dry, and the combination of thick gloves and care are necessary. Even if you can’t see it, moss and slime may have worked its way into the joints, and rust may have built up around the clips and joints. Each of these may cause problems if not handled carefully and patiently. Run the blade of the screwdriver along the edge where moss has grown and it should come off very easily.

Lift panes well clear of the clips before handing them to your helper.

With the top panes out, move on to the lower ones. If the sizes of glass differ, make a diagram with notes before taking them out. It will seem like a waste of time, perhaps, but will save you time and frustration in the end.

When removing glass from the walls, tip the top edge out first, then lift outward so that the pane is flat, parallel with the ground. This will reduce the chances of dropping panes. The panes always come out toward the outside of the greenhouse (upwards in the case of the roof), never inwards. For this reason, it is worthwhile to clear the area around the greenhouse of brambles or other obstacles that might get in the way.

Transporting Glass

Strap the glass securely for transport. It helps to place something soft between panes to reduce the chance of breakage. Tea towels, regular towels, or even tee shirts are great for the job, but any soft material should do. Place the glass panes on edge, rather than flat against the floor. This will make it so that each pane only supports its own weight, rather than having the pane on the bottom support the whole lot. Glass is also stronger on end than laid flat. Make sure it can’t slide or tip, and you should be ready for safe transport. It is also best to move glass in a boot or the back of a van, rather than in the passenger areas.

Doors and Vents

Once the glazing is off and securely stored, the door comes next. Remove the bracket that keeps it from sliding free, and it should slide off the end of the track and come free. If it is a hinged door, simply remove the pins of the bolts that hold it in place (the bottom one first usually works best) and lift it outward to free it.

Next, remove the roof vents. These should lift up slightly and slide along the roofline and out at the ends. Dirt sometimes makes this track a bit rough, but with some wiggling and careful persuasion it should come free. There is a variety of stoppers that might be in place to keep the vent from moving side to side, but these should be easy to remove, sometimes requiring removal of a screw. Some greenhouses have automatic openers that need to be removed before the vents will move – this is usually the small matter of a few screws.

Next, we remove the slam bars. There are usually two bolts that hold these in place. Loosen these bolts (sometimes they need to be removed completely), then slide one bar down until it comes away from the glazing bars.

If the bolts are so corroded that they sheer off, there is a good chance that all of the greenhouse’s bolts are similar and will need special effort to remove. It is possible to leave all of this intact and move it as a section, but it is weak and will likely bend out of shape during transit or loading/unloading. These parts are also usually unique to each manufacturer, so replacing a damaged piece may prove difficult.

Roof And Frame

Next, remove the roof bars by undoing the bolts at the top and bottom. These should be fairly easy, unless steel screws were used. If this latter is the case, they are very difficult to remove and sometimes prove impossible. You may need to invest in a new bar if this happens. They are fairly interchangeable though, so if you do have a problem, it is not insurmountable.

Unfasten and remove the glazing bars as you go along. If the bolts are shearing off, then tighten them instead of trying to loosen them, and they will break away more easily.

Next, remove the two bolts that hold on each end of the ridge bar. Once loosened, the bars usually slide out without a problem. It is a good idea to have some help for this stage though, as the bar is long, and it is a much easier job with two pairs of hands on it.

Now you should be left with four walls. This is a good time to unfasten them from the base. The means by which greenhouses are fastened varies a lot, so it is difficult to give advice here, but in most cases the method of removal will be fairly intuitive. Once you have unfastened the walls from the base, the only thing holding the greenhouse in place should be the bolts at the corners, one at the base and two at the top.

Greenhouses vary in this respect too. Untighten the bottom bolt and slide it away from the junction. The nut tightens over the top bar of the side section. Completely remove the top nut so that the roof corner support bar can be removed. The bolt should now be free for removal, sliding up and out from the junction. Once both bolts are removed, the side bar is free to slide out. The top of this section of the greenhouse should now be unfastened.

The bottom junction, in our sample, is removed in the same manner as the top one, except that there is only one bolt holding the side and end sections together. Once unfastened, the structural integrity of the greenhouse is released, and it is a very good idea to have extra help on hand. The wall may sag, bend or even flap around once freed, and any of these distortions may cause damage.

It is best to free up one wall at a time and set each aside in a stable place before taking on the next one. A few helpers would be of use at this stage, as one can help move the wall section away while the other two hold up the now-unstable walls that are still attached. The more that is removed, the less there is to hold, but the less table they will be too, so we recommend three helpers for this part, and maybe more if the greenhouse is quite large.

If you can transport these sections intact, that is the easiest way to go, but if you need to dismantle them even further, take pictures and notes first. You may also want to use a sharpie to label each part too, for clearer grouping and assembly later on – especially if there is a significant passage of time between taking the greenhouse apart and trying to put it back together again. A small mistake early on can mean a lot of backtracking later and can greatly increase the length of the job and the frustration it creates.

Once ready to erect the greenhouse again, simply follow the same steps you did for dismantling it, but in reverse. Special care must be taken, however, to ensure that the foundation and assembly is square – if angles are off on the frame, the square panes of glass won’t fit into the spaces they should, and the greenhouse cannot be fully assembled.

A big part of this is making sure the foundation is level too; the gutters and base should be perfectly parallel. As with most things, a good foundation is the key to the whole thing.

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matt garner Author: Matt Garner
I'm an amateur gardener based in Birmingham in England, utilising my 30 years experience to help others learn all about gardening for South West Greenhouses. My specialist expertise are with assembling and dismantling greenhouses of all shapes and sizes. I've spent countless years growing fruit and vegetables at Walsall Road Allotments, and I was also a proud member of the Balsall & District Horticultural Society for many years. Linkedin | Twitter