Making new skirtings and architraves

[kereru]

Ok all you wood working guys out there, I need your advice. A woman doing 'do it yourself', yes I know, but 'bear' with me please. I want to make new skirtings and architraves for my house. I plan to make them out of 18mm thick mdf. My present skirtings and architraves are miserable specimens hence why I would like to change them to something more chunky and modern. I am also fitting new t & g flooring so the skirtings need to go anyway.
I can only fit in 80mm wide architraves ( in the tightest locations) so 80 it is and my skirtings will be 90mm high. I plan to cut them out of 600mm wide sheets. This is reasonably cost effective and I can just about man handle a sheet of this width, 2400mm long. My question is this, do I need to cut grooves in the back of my skirtings and architraves?? All the ready made ones that you buy have some sort of grooves in them. Is this a result of the making process or are the grooves there for a reason, eg, movement?? or to stop the board cupping maybe.??
Appreciate your help and advice please.................

 

[Mar_mite]

You won't need to put grooves in the back. Mdf doesn't cup. All the pre-bought mdf skirting if used wasn't grooved. Mdf is very stable and won't cup or twist.
I would use moisture resistant mdf, especially on the skirting, where you might run a mop against it. Hope this helps.

 

[kereru]

Thank you for your reply to my question. Yes mdf is very stable, but the ready made skirting and architrave does have grooves in it and I wondered why, if it was not for some very specific reason.
Anyway, if anyone else has any thoughts I would appreciate them!!!!!

 

[beech1948]

I simply would not make skirting and architrave from MDF. I would buy ready made with mouldings from a local timber merchant. Cut to size, mitre,cope, fit.

Al

 

[Random Orbital Bob]

I think the grooves in wood are probably two fold: A) to help with cupping avoidance across the grain as the wood shrinks through drying and b) to assist in the purchase of construction adhesives because in some modern scenarios architraves and skirting are glued (gripfill type products) to the wall and then lightly pinned with a thin (16 gauge) nail, usually from a gun.

In the case of mdf, because it has no grain there is no risk of cupping. The risk comes from sucking up spilt moisture (hence the posters reference to a mop) and then "blowing" which is when the mdf kind of swells and puffs up and loses its shape and strength. That's also why the advice is to choose MR MDF or moisture resistant MDF because that is far superior at resisting the sucking up of moisture.

So...don't worry about the grooves, but do worry about getting MRMDF (it is more expensive). Also mdf is a perfectly good material to use in both skirting and architrave applications because its so stable and it takes paint beautifully. Its very widely used in modern build so I would assert you should not be put off by posters who express a personal preference for wood. In my view you're on a reasonable track, you just need to make sure the mdf is as waterproof as possible, hence the MR discussion.

 

[Random Orbital Bob]

Just to add some graphic to that discussion. Here are a couple of snaps of skirting and architraves from mdf painted with Chalky Downs 2 (Dulux) and a built in I made to match whilst wrapping the skirting. (Chalky Downs 5 for contrast but match). Doors are oak. Also just to show the versatility of mdf (in a contemporary setting) a couple of rad covers too.

 

[MMUK]

The grooves in manufactured MDF skirtings are for retaining clips and therefore not necessary. HTH

 

[blackrodd]

Dust, Dust! Don't forget the dust is really rather lethal, so make sure you are well protected when using the saw bench, a spindle moulder, planer, or router.
And have a good extraction system in place or do it outside with you're mask on!
Moisture resistant mdf is really good for this job, because of it's stability and low wastage.
when machined, the moulding/cutting action makes the newly cut area "woolly".
After the primer coat has dried, you can sand the new edges and mouldings for a smooth finish, so therefor picking a fairly simple mould for the skirtings and architraves would probably be a good idea.
HTH Regards Rodders

 

[Random Orbital Bob]

One last thing to bear in mind, certainly here in the UK though that may not be the case in NZ....we can get pre-primed and pre-moulded mdf for exactly the use you're proposing. The pictures I posted were of exactly that ie they were purchased in 5m lengths and the skirting is 10" high with the molding already cut in. The architrave incidentally is actually the skirting with some of the straight edge ripped off because I couldn't buy architrave wide enough for my double doors (didn't look chunky enough for the size of space. But the fact its already white and pre primed makes a lot of time and money saved at the finish painting stage. Is your need to keep the cost as low as possible and hence cutting it direct from sheet goods? Its just you're taking the long route that's all. But if its budget constraint I understand. Rodders comments about dust are extremely important. MDF dust is a known carcinogen because of the resins released when machined. You would be advised to use a good quality certified mask like the 3M 7500 or similar. Don't use those flabby, elastic strapon cheap rubbish ones....worse than useless.

 

[kereru]

Wow thank you all for your great contributions, you are fabulous guys!!!!!! And the pictures of your handiwork are really beautiful, fancy a holiday in NZ????? I could do with some help............
Yes I could buy ready made and yes it comes primed both sides, but the choices of what is available off the shelf are not great. Very thin, with a curved or chamfered edge, rather miserable. I guess in an ordinary standard house that is fine and probably no one would notice the difference, but sorry guys I am a designer so I notice everything!!!!!!! It's a pain actually but I cannot change the beast, so I have to go down this difficult route. I have made cupboards and shelves in the past with mdf and successfully painted them and the result was pretty good. Here I can only buy 'mdf', but what I have done where I used in it in a situation where there was any chance of water I varnished the bottom edge, even kitchen makers do not do this on their worktops when they set in a sink or hob and really it only takes a few minutes to do this. Gaskets can leak!!!!
Yes I plan to glue so I did wonder if a groove might be useful in facilitating space for this. Glues are so strong these days, only problem comes when you want to take it off, but I hope I don't plan for that any time soon!!!
As for fixing real wood, here is another question..............I am going to put cedar fascias around my windows. My house is timber frame with a stucco finish, render in English terms. My windows are powder coated aluminium. The cedar is 100mm wide and 19mm thick. Again I plan to glue it on with two sorts of glue. A contact adhesive for quick grab and a longer term waterproof glue. To put in mechanical fixings would be difficult, expensive and not look good. So what do you think about grooves in the back of the cedar???? Most of the cedar is quite well protected under the eaves of the roof but not all of it. Our sun here is pretty destructive but it is always breezy at some point in the day and so if it has rained it dries quick.
So what do think about that.?????
And yes don't worry I know all about mdf dust, it makes me sneeze something rotten!!!!!!!
Hugs guys you are wonderful.

 

[kereru]

Nice lighting too, you obviously have a good eye for detail.

 

[blackrodd]

With regard to fixing the fascias, as timber is a natural product, it is very likely to move, personally,glueing on it's own would not be as long lasting and secure as pinning and glue might not allow a small amount of movement that's advisable to allow for.
I would suggest that as you seem to have lots to do that you buy a decent finishing nail gun and secret nail you're cedar work with exterior quality nails.
Another idea is You could incorporate cover strips on the ends/corners.
These nail guns are very good and "discreet" leaving very little sign of nailing having taken place.
A finishing nail gun would be excellent on the skirtings and architraves mentioned previously.
HTH Regards Rodders

 

[Random Orbital Bob]

+1 to the nail gun. Don't forget the reason cedar is often chosen as an outside finish is that, much like oak it's very weather resistant so its a good choice. In the UK when we clad an exterior wall in feather edge or similar overlapping style wood finishes, it is typically done with a nail finish. The nails are secreted underneath the overlap of the following board so appear invisible when complete. I would suggest maybe consider hiring one just for the job. They are either pneumatic in which case you have a compressor and hose attached or (better for outside work) gas or battery powered in which case they're free standing and easier to manoeuvre (but more expensive). But...you said fascia so I'm guessing your cedar won't overlap?? In which case if you wanted to avoid mechanical fixings showing you could counterbore, screw and plug the holes with wooden plugs cut from the same cedar (offcuts). If you're judicious about the choice of where you cut the plug from you can usually match the grain pretty well and once in sand it flush and they're nearly invisible. The prevailing "culture" in the UK is generally not to glue boards in exterior applications like you suggest, rather use fixings of one type or another. There's no reason you shouldn't try a decent strong glue though, as long as you can approximate some form of clamping arrangement while it sets up, it should work.

Your comments about my house are most kind

 

[kereru]

Oh boy I have typed a reply twice now and both times I just got logged out, so maddening!!!!!

 

[kereru]

And then it sent it. !!!!
Thanks again for your help. I have a nail gun with compressor from a friend. I plan to use it for fixing my T&G flooring, and NO I am not making it!!!!!!!!! I do not know if nails would go into the stucco though, it's as hard as.
But you didn't answer my question of grooves in the back of the cedar??? If not needed for movement then maybe for glue?
Yes I am busy!!!!!!!
Look forward to hearing from you in the morning, sleep well.
zzzzzzzzzzzzzzz

 

[kereru]

Hi Al, yes wood is beautiful, but every situation is different and because I want a painted effect I think to use wood, would be a little wasteful. Also it does not always paint up as well as mdf. I am a natural products person but everything has it's place and it's use. And sometimes mdf has its uses!!!!!! Who invented it anyway???

 

[Random Orbital Bob]

LOL...I like your style

You know I really don't know why the grooves are manufactures in the external cedar. I'm pretty sure they don't do that here. Maybe your summer sun is known to dry the boards out so fast that they cup and split more than we do. On the other hand my understanding is that NZ weather is not dis-similar to our own (that would be rain then!!)

 

[kereru]

Hi Bob, pretty much everything here is bespoke, it is such a small market. So the cedar boards have been cut to my specification. It is me that is wondering if I need grooves in the back before I stick it on the stucco. I have borrowed a Dewalt saw bench but I cannot see a way of lowering the saw, much as I have studied it. So, if I do put grooves in the back it will have to be with a skill saw. A bit tedious but if necessary I will do it.
Weather is much better than UK. Nelson where I live has great sun hours and is generally a dry atmosphere, very rarely humid. It does rain of course but generally it does not last for days and the sun always seems to shine again. Cars don't seem to go rusty so quickly, and wet and dry rot are unusual in house timbers. But temperatures can vary widely. The night before last it was 6 degrees C with snow on the mountain ranges and frost inland. But today it has warmed up again, the snow all gone, and back to a balmy autumn. The 1st March was the first day of autumn here.
Cheers for all your help, hugs from your Kiwi bird..........

 

[Random Orbital Bob]

I'm struggling to see why you would groove the cedar...I don't think I would. I'm familiar with Stucco as I've friends in the States and they use it there all the time (rendered finish over a chicken wire net basically and then they texture the finish with a stipple type effect so its quite rasping to the touch). Horrible stuff! But once its dry its pretty stable so I cant see the need for grooves?? I may be missing something though. Maybe phone a builders merchant and ask if its common practice, when they've stopped sniggering at the idea of a woman doing DIY they might answer

 

[kereru]

Well if I don't need to I won't, it's all extra work. Thought you would be asleep Bob??
The stucco is pretty stable and pretty hard............but the timber frame behind it does flex a bit, especially if we have a little shake.
Yes I could ask in the timber yard, but everyman and his dog has their own opinions which are not always correct.
But thanks again.