An old adage when to comes to farm buildings is “build it twice as big as you want and it will end up half the size you need”. You will be familiar with the sentiment; the farm always outgrows the buildings and silage clamps are no different.  So what do you do when you run out of room and you’re left scratching your head looking for space. Previously in this series we have looked at overloading silage clamps and how you can squeeze a quart into a pint pot, but that only goes so far. In the short term it’s common to bale some “excess” silage but it’s not a solution for every situation.

Baled silage can be useful for young stock or sheep when the feeding system is different from the main herd, but where a complete diet mix is used; bale silage is not really suitable. The variability between bales makes the ration “variable” and the time needed to open and load the bales makes them unsuitable for large scale use for cattle and AD plants alike.

So how do you find more clamp space?

Well you can start from scratch with a green field site but with some careful planning, you might just be able to make the most of your existing clamps. The solution will probably come from one of the following:

·      Increase storage height

·      Increase the clamp length

·      Add an additional clamp to one side

To successfully do any of the above – you need to have planned for extra storage at the outset. Ideally you planned for expansion when you were designing the initial clamps, this will make your life so much easier when you need to find some more space.

How to design for future expansion.

Let’s start with increasing storage height. If you need to go higher, you need to have a very specific clamp design to safely do this. If you have a clamp constructed with precast L shaped panels or prestressed cantilever panels, then the wall height can’t be increased. If you have earth walls, or post and panel walling (either timber or concrete) then it may be possible. But before you order some more wall planks, just hang on a moment – the support columns need to have been designed for this!

I’m regularly asked if another row of panels can be stuck on top of the existing walls to take the walls up a bit higher. “There isn’t much load, it’s only a couple of feet of silage at the top of the wall” is so often stated. But the problem isn’t at the top of the wall – it’s at the bottom. The load on the wall can be described as triangular, the maximum load is at the base and the load reduces until you get to the top of the wall where there is virtually no load at all. By increasing the height, the width of the triangle increases massively and the load at the base will become huge.

Unless the columns and the foundations were designed for this load at the outset, something is going to fail – and then the whole structure is destroyed. It’s unlikely this will be a immediate, catastrophic failure as there will be some safety factor in the design. What it will mean is that the lifespan will be reduced as the safety factor is there for the long term protection of the structure.

How do you know what the building is designed for?

Due to the economic marketplace, the chances are that the clamps will only be designed for what you (or whoever ordered the clamps) required at the time. Adding extra capacity to a column and its foundations costs money and any builder who added that in at quote stage would be priced out of the work. For an example, to go from 3m high to 4m high on a 4.5m bay, the weight of the steel columns jump from 54 kg/m to 82 kg/m!

So unless you planned for extra storage – going higher is unlikely.

What about increasing the length of the clamps?

The practicality of increasing clamp length will depend on the site layout. There are two main things to consider, the access to the front and the falls on the floor. The other buildings and roadways on the site will determine if a clamp can be extended at the front. The levels will determine what falls you can achieve to get effluent and rainwater away from the face. But what about extending out backwards? How likely is that?

Well this depends on the floor falls again, but it can be possible even if it may be expensive. If you went for a back wall in the initial clamp, then this needs to be relocated. If the wall is columns and panels then the panels at least can be reused. If the construction is insitu concrete, cast-in precast or prestressed vertical cantilever panels, then it’s unlikely they can be used again. Of course you can reconfigure the clamp without a back wall. Ideally you would have planned ahead and put in a back wall using a movable wall solution so this can be easily relocated.

And finally, increasing clamp width – or more likely, adding another clamp along side.

This is the most likely option for adding a significant increase in storage capacity. It’s also the easiest solution for most site layouts. By using a bit of prior planning, it’s possible to make adding a clamp significantly cheaper and easier. By specifying “double loading” walls in your initial clamp design, you give yourself the option to use the sidewall in one clamp as a dividing wall when you extend to a double clamp. This costs very little extra in the initial clamp build but will save you a whole wall when it comes to extend the storage space.

The best way to build extra storage silage space is to plan for it at the very beginning, that way you might just save yourself a deal of stress and headache, along with a significant amount of money.

If you want to discuss how you can extend your existing clamps or how to design your clamps for future expansion or to discuss any of the other aspects of silage making covered in this series – contact Jeremy Nash @ jeremynash1@btinternet.com