FAQ · TV aerials & reception · SE Queensland
My TV aerial is in the roof. Will insulation affect the reception?
For nearly every home, no. Pumped cellulose is paper fibre and doesn’t meaningfully block a TV signal. What attenuates a roof-cavity aerial is the foil in sarking or anticon, the metal layer, not the insulation.
I get this one a fair bit from people with the aerial tucked up in the roof space. It’s a sensible question, and it deserves the honest mechanism rather than a brush-off. Here’s what actually affects a roof-cavity aerial, why the insulation isn’t the culprit, and the real fix if your reception was already on the marginal side before we turn up.
Paper fibre isn’t what blocks a TV signal.
Start with what cellulose actually is. It’s recycled paper milled into fibre and treated with a little borax. Fibre and trapped air, nothing more. There’s no continuous sheet of metal in it, and metal is the thing that reflects or soaks up the UHF radio waves that carry your digital TV. A blanket of paper fibre sitting on top of your ceiling is, for all practical purposes, see-through to that signal. That’s as true of polyester or glasswool batts as it is of cellulose. Bulk insulation is fibre and air, not a shield.
So if your reception is clean today, pumping cellulose across the ceiling won’t change it. The insulation lies on top of the plasterboard ceiling, down in the cavity, while most roof-cavity aerials sit up higher near the ridge, and even where they’re close, the fibre simply isn’t a material that knocks the signal about. I’ve pumped cellulose into thousands of roofs with the aerial sitting right there, and a paper-fibre blanket isn’t what makes or breaks the picture.
“Cellulose is paper and air. There’s no metal in it to bounce a TV signal. If your reception goes off after a roof job, look at the foil and the aerial, not the insulation.”Peter Johnson, Comfort Zone Insulation Team
What actually shields the aerial
It’s the foil in the roof, and the roof sheets, not the insulation.
The thing that genuinely affects a roof-cavity aerial is metal. A foil-faced sarking membrane or a foil-backed anticon blanket rolled out under the roof sheets puts a partial metal layer between your aerial and the broadcast tower, and a steel or aluminium roof does the same. The Australian Government’s yourhome guide describes reflective foil working through its shiny reflective metal surface , that metal facing is the layer that does the job for heat. In my experience the same metal that reflects radiant heat will also reflect some radio waves, which is the part that touches your aerial.
So if you’ve got foil sarking or anticon up there and an aerial in the cavity, the membrane was already affecting your signal long before any ceiling insulation went in. That’s the bit worth understanding: the metal in your roof is the partial shield, and the paper-fibre blanket we pump onto your ceiling isn’t. Blaming the insulation for a foil-and-roof reception problem just sends you fixing the wrong thing.
The honest fix
Already marginal? Get the aerial outside, regardless of insulation.
Here’s the straight version. If your reception is already pixelating or dropping out before we ever turn up, the real fix isn’t about the insulation at all. It’s the aerial position. An aerial sitting in the roof cavity is fighting the roof sheets and any foil membrane above it for a clear line to the tower, so it’s working with a handicap from the start. Move it to an outside wall bracket or a roof-mounted mast and you clear that obstruction in one go.
- A roof-cavity aerial sits behind the roof sheets and any foil sarking or anticon. A partial metal shield it has to punch through.
- An outside or roof-mounted aerial gets the antenna out into clear line-of-sight to the broadcast tower.
- It's an antenna-installer's job, not an insulation one, and usually a modest cost.
- It fixes a marginal signal far more reliably than worrying about what's on top of your ceiling.
I’d rather tell you that plainly than have you blame a paper-fibre blanket for a reception problem the roof itself was already causing. We pump cellulose across the ceiling as one seamless blanket and tidy up after ourselves, and the photos are checked before you’re invoiced, but a roof-cavity aerial is one I’ll always be honest about. Get it outside and the question takes care of itself. That’s our system, the same on every job, run by Comfort Zone franchise owner-operators trained to one standard and held to it.
More on insulation, aerials & signal
My TV aerial is in the roof. Will insulation affect the reception?+
In the great majority of homes, no, not in any way you'd notice. Pumped cellulose is recycled paper fibre treated with a little borax, and paper fibre is close to transparent to the UHF radio waves that carry digital TV; it doesn't have a metal layer to bounce or soak up the signal. What does attenuate a roof-cavity aerial is metal: a foil-backed sarking or anticon blanket under the roof sheets, or the metal roof sheets themselves, form a partial shield between the aerial and the broadcast tower. So if your reception is fine now, ceiling insulation isn't going to change it. If it's already marginal, pixelating or dropping out before we ever turn up, the honest fix is moving the aerial out of the cavity to an outside or roof-mounted position, regardless of what insulation you choose.
Does the insulation itself block a TV signal, or is it the foil under the roof?+
It's the foil, not the insulation. Bulk insulation, whether cellulose, polyester or glasswool batts, is made of fibre and air, with no continuous metal layer, so it's essentially see-through to a TV signal at the levels we install. The thing that genuinely shields a roof-cavity aerial is the metal in the roof: a foil-faced sarking membrane or a foil-backed anticon blanket rolled under the sheets, plus a steel or aluminium roof itself. The Australian Government's yourhome guide describes reflective foil as working through its shiny reflective metal surface, and that metal facing is the layer that does the job for heat. The same metal that reflects radiant heat will also reflect some radio waves, which is the part of the physics that touches your aerial. So if you've got foil sarking or anticon up there and a roof-cavity aerial, the membrane was already affecting your signal long before any ceiling insulation went in.
My reception is already a bit dodgy. Should I get an outside aerial before insulating?+
If it's already pixelating or dropping out, yes. Sort the aerial first, and do it regardless of insulation. An aerial sitting in the roof cavity is fighting the roof sheets and any foil membrane above it for line-of-sight to the tower, so it's working with a handicap before insulation enters the picture. Moving it to an outside wall bracket or a roof-mounted mast clears that obstruction and almost always fixes a marginal signal far more reliably than worrying about what's on top of your ceiling. It's an antenna-installer's job, not an insulation one, and it's usually a modest cost. I'd rather tell you that straight than have you blame the insulation for a reception problem the roof itself was already causing. Get the aerial outside and the question answers itself.
Will pumped cellulose interfere with my WiFi or mobile signal in the house?+
No, not in any way you'd notice. Cellulose is paper fibre and air, with no metal sheet in it to reflect or absorb a radio signal, so a blanket of it sitting on top of your ceiling doesn't block the WiFi between your rooms or the mobile reception inside the house. The materials that genuinely knock signal around in a home are the metal ones: foil-backed sarking and anticon under the roof, foil-faced plasterboard, metal roof sheets, brick and concrete. A paper-fibre ceiling blanket isn't in that league. If anything, the homes where people notice mobile or TV signal trouble are the ones with a lot of foil and steel in the roof, and again, that's the roof membrane and the sheets doing it, not the insulation we pump across your ceiling.
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Aerial in the roof and worried about insulation? Call Peter on 0414 586 315 , I’ll give you an honest answer for your roof, not a sales pitch.